Comparative transcriptomes reveal the disjunction adaptive strategy of Thuja species in East Asia and North America

The genus Thuja is ideal for investigating the genetic basis of the East Asia-North America disjunction.The biogeographical background of the genus is debatable and an adaptive strategy is lacking.Through the analysis and mining of comparative transcriptomes,species differentiation and positively selected genes(PSGs)were identified to provide information for understanding the environmental adaptation strategies of the genus Thuja.De novo assembly yielded 44,397-74,252 unigenes of the five Thuja species with contig N50length ranging from 1,559 to 1,724 bp.Annotations revealed a similar distribution of functional categories among them.Based on the phylogenetic trees constructed using the transcriptome data,T.sutchuenensis was divided first,followed by T.plicata and T.occidentalis.The final differentiation of T.koraiensis and T.standishii formed a clade.Enrichment analysis indicated that the PSGs of the North American Thuja species were involved in plant hormone signal transduction and carbon fixation of photosynthetic organisms pathways.The PSGs of East Asian Thuja were related to phenolic,alkaloid,and terpenoid synthesis,important stress-resistant genes and could increase plant resistance to external environmental stresses.This study discovered numerous aroma synthetic-related PSGs including terpene synthase(TPS)genes and lipid phosphate phosphatase 2(LPP2),associated with the synthetic aroma of T.sutchuenensis.Physiological indicators,such as the contents of soluble sugars,total chlorophyll,total phenolics,and total flavonoids were determined,which are consistent with the PSGs enrichment pathways associated with adaptive strategies in the five Thuja species.The results of this study provide an important basis for future studies on conservation genetics.

Comprehensive analysis of coding and non-coding RNA transcriptomes related to hypoxic adaptation in Tibetan chickens

Background:Tibetan chickens,a unique native breed in the Qinghai-Tibet Plateau of China,possess a suite of adaptive features that enable them to tolerate the high-altitude hypoxic environment.Increasing evidence suggests that long non-coding RNAs(lncRNAs)and microRNAs(miRNAs)play roles in the hypoxic adaptation of high-altitude animals,although their exact involvement remains unclear.Results:This study aimed to elucidate the global landscape of mRNAs,lncRNAs,and miRNAs using transcriptome sequencing to construct a regulatory network of competing endogenous RNAs(ceRNAs)and thus provide insights into the hypoxic adaptation of Tibetan chicken embryos.In total,354 differentially expressed genes(DE genes),389 differentially expressed lncRNAs(DE lncRNAs),and 73 differentially expressed miRNAs(DE miRNAs)were identified between Tibetan chickens(TC)and control Chahua chickens(CH).GO and KEGG enrichment analysis revealed that several important DE miRNAs and their target DE lncRNAs and DE genes are involved in angiogenesis(including blood vessel development and blood circulation)and energy metabolism(including glucose,carbohydrate,and lipid metabolism).The ceRNA network was then constructed with the predicted DE gene-DE miRNA-DE lncRNA interactions,which further revealed the regulatory roles of these differentially expressed RNAs during hypoxic adaptation of Tibetan chickens.Conclusions:Analysis of transcriptomic data revealed several key candidate ceRNAs that may play high-priority roles in the hypoxic adaptation of Tibetan chickens by regulating angiogenesis and energy metabolism.These results provide insights into the molecular mechanisms of hypoxic adaptation regulatory networks from the perspective of coding and non-coding RNAs.

Comparison of transcriptomes undergoing waterlogging at the seedling stage between tolerant and sensitive varieties of Brassica napus L.

RNA sequencing of the sensitive GH01 variety of Brassica napus L. seedling roots under 12 h of waterlogging was compared with previously published data of the ZS9 tolerant variety to unravel genetic mechanisms of waterlogging tolerance beyond natural variation. A total of 2 977 genes with similar expression patterns and 17 genes with opposite expression patterns were identiifed in the transcription proifles of ZS9 and GH01. An additional 1 438 genes in ZS9 and 1 861 genes in GH01 showed strain speciifc regulation. Analysis of the overlapped genes between ZS9 and GH01 revealed that waterlogging tolerance is determined by ability to regulate genes with similar expression patterns. Moreover, differences in both gene expression proifles and abscisic acid (ABA) contents between the two varieties suggest that ABA may play some role in waterlogging tolerance. This study identiifes a subset of candidate genes for further functional analysis.

Transcriptomes of early developing tassels under drought stress reveal differential expression of genes related to drought tolerance in maize

Tassel, the male reproductive organs in maize, its development is adversely affected by drought during tasseling. To determine drought tolerance mechanisms of tassel differentiation at transcriptome level, RNA-Seq was performed using RNA of early developing tassel from 10 maize inbred lines under well-watered （control） and drought-stressed conditions, respectively. Results showed that the most active pathway for drought stress in maize were related to metabolic regulation at RNA level. And some genes, encoding enzymes involved in carbohydrate and lipid metabolism, were significantly down-regulated in drought-stressed plants. While, the transcription factors and genes, encoding catabolic or degradative enzymes, were over-expressed in maize early developing tassels under drought-stressed conditions, and among them, the transcripts of genes encoding exon-junction complexes involved in ＇RNA transcript＇ and ＇mRNA surveillance＇ pathways were significantly affected by drought stress. In addition, many other genes related to drought stress showed transcriptional changes at the later period of stress.

Comparative analysis of transcriptomes from albino and control sea cucumbers, Apostichopus japonicus

The sea cucumberApostichopus japonicus is an important economic species in China. Its dorsal body wall color is commonly tawny, whereas its ventral surface is fawn. Albino sea cucumbers are rarely observed. In order to profile gene expression and screen albinism-related genes, we compared the transcriptome of albino samples with a control by 454 cDNA sequencing. We found that 6 539 identified genes on the basis of sequence similarity to known genes were expressed in the albino A. japonicus. The gene ontology analysis indicated that the transcription of genes associated with the terms of biological regulation and pigmenta-tion was non-abundant in the albino library compared to the control. Based on an analysis using the Kyoto Encyclopedia of Genes and Genomics （KEGG） database, we identified 14 important genes that were in-volved in major intercellular signaling pathways related to melanin synthesis, such as tyrosine metabolism, the mitogen-activated protein kinase （MAPK） pathway, and melanogenesis. The expressions of fibroblast growth factor receptor 4 （FGFR4）, protein kinase C （PKC）, protein kinase A （PKA）, and Ras genes were sig-nificantly down-regulated in the albino transcriptome compared with the control, while the expressions of homogentisate 1, 2-dioxygenase gene （HGO）, cAMP-responsive element binding protein （CREB）, transcrip-tion factor AP-1（c-jun）, and calmodulin （CaM） were significantly up-regulated （Fisher＇s exact test,p 〈 0.05）. These differentially expressed genes could be candidate genes for revealing the mechanism of albinism and investigating regulation of melanin synthesis inA. japonicus.

Assembly and Analysis of Changes in Transcriptomes of Dairy Cattle Rumen Epithelia during Lactation and Dry Periods

Lactation in dairy cattle is coupled with increased nutrient requirements for milk synthesis. Therefore, dairy cattle metabolism has to adapt to meet lactation-associated challenges and requires major functional adjustments of the rumen and whole digestive system. This report describes the use of next-generation sequencing technology for assembly and profiling of the transcriptome of cattle rumen epithelial tissues from cattle in both dry and lactation periods. Transcriptomics profiling and comparison revealed extensive changes in gene expression related to metabolism in rumen epithelial tissue due to the adaptation to lactation. Ruminal epithelial adaptation to the challenges of metabolism and high nutrient requirements during lactation is presumably the primary triggers for these alterations in gene expression. Principal component analysis (PCA) indicated that the gene expression profiles of the rumen epithelia from dry and lactating cattle fall into two very distinct clusters. Gene Ontology (GO) enrichment analysis revealed that the most GO terms were related to various metabolic processes in lactating cattle. The most significantly (false discovery rate (FDR) p-value < 0.05) enriched GO term in biological processes was “carbohydrate derivative metabolic process”, followed by “nucleoside metabolic process”. Up-stream regulators, such as PPARA (Peroxisome proliferator-activated receptor alpha) gene, and up-regulated genes of molecular transporters are the focal points of this report.

Generation and classification of transcriptomes in two Croomia species and molecular evolution of CYC/TB1 genes in Stemonaceae

The genus Croomia(Stemonaceae) is an excellent model for studying the evolution of the Eastern Asia(EA)-Eastern North America(ENA) floristic disjunction and the genetic mechanisms of floral zygomorphy formation. In addition to the presence of both actinomorphic and zygomorphic flowers within the genus, species are disjunctively distributed between EA and ENA. However, due to the limited availability of genomic resources, few studies of Croomia have examined these questions. In this study,we sequenced the floral and leaf transcriptomes of the zygomorphic flowered Croomia heterosepala and the actinomorphic flowered Croomia japonica, and used comparative genomic approaches to investigate the transcriptome evolution of the two closely related species. The sequencing and de novo assembly of transcriptomes from flowers of C. heterosepala(ChFlower), flowers of C. japonica(CjFlower), and leaves of C. japonica(CjLeaf) yielded 57,193, 62,131 and 64,448 unigenes, respectively. In addition, estimation of Ka/Ks ratios for 11,566 potential orthologous groups between ChFlower and CjFlower revealed that only six pairs had Ka/Ks ratios significantly greater than 1 and are likely under positive selection. A total of 429 single copy nuclear genes(SCNGs) and 21,460 expression sequence tags-simple sequence repeats(ESTSSRs) were identified in this study. Specifically, we identified seven CYC/TB1-like genes from Stemonaceae. Phylogenetic and molecular evolution analyses indicated that these CYC/TB1-like genes formed a monophyletic clade(SteTBL1) and were subject to strong purifying selection. The shifts of floral symmetry in Stemonaceae do not appear to be correlated with TBL copy number.

Transcriptomes of Litopenaeus vannamei reveal modulation of antioxidant system induced by dietary archaeal carotenoids

Oxidative stress induced by factors such as ammonia nitrogen has become a major issue in shrimp farming.The effects of carotenoids on the growth and antioxidant capability of Litopenaeus vannamei juveniles were investigated in this study using dietary archaeal carotenoids supplementation.For four weeks,shrimp were given diets containing 0 mg/kg(Ctrl)and 55.98 mg/kg(Car)archaeal carotenoids.Dietary archaeal carotenoids significantly enhanced the astaxanthin content in shrimp muscles and carapaces,as well as the superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)activity(P<0.05).The malonaldehyde(MDA)content in Car group significantly decreased(P<0.05).The transcriptome analysis was conducted to determine the molecular processes in response to archaeal carotenoids supplementation.A total of 1536 differentially expressed genes(DEGs)were detected,including 538 upregulated DEGs and 998 downregulated DEGs.GO functional enrichment analysis between Ctrl and Car indicated that 26 GO terms including extracellular region,metabolic process,and proteolysis were enriched.The KEGG pathway enrichment analysis revealed that the amino sugar and nucleotide sugar metabolism,cysteine and methionine metabolism,glycine serine and threonine metabolism,and amino acid biosynthesis were enriched.Archaeal carotenoids influenced the expression of several important genes involved in reactive oxygen species(ROS)generation,Nrf2 signaling,and antioxidant enzymes.Seven DEGs were chosen to confirm the RNA-Seq data using qRT-PCR.The genes and pathways discovered in this work assist to elucidate the molecular processes through which archaeal carotenoid enhances L.vannamei antioxidative system.

Tandem repetitions in transcriptomes of some Solanaceae species

Characterization of occurrence, density and motif sequence of tandem repeats in the transcribed regions is helpful in understanding the functional significance of these repeats in the modern genomes. We analyzed tandem repeats present in expressed sequences of thirteen species belonging to genera Capsicum, Nicotiana, Petunia and Solanum of family Solanaceae and the genus Coffea of Rubiaceae to investigate the propagation and evolutionary sustenance of these repeats. Tandem repeat containing sequences constituted 1.58% to 7.46% of sequences analyzed. Tandem repetitions of size 2, 15, 18 and 21 bp motifs were more frequent. Repeats with unit sizes 21 and 22 bp were also abundant in genomic sequences of potato and tomato. While mutations occurring in these repeats may alter the repeat number, genomes adjust to these changes by keeping the translated products unaffected. Surprisingly, in majority of the species under study, tandem repeat motif length did not exceed 228 bp. Conserved tandem repeat motifs of sizes 180, 192 and 204 bp were also abundant in the genomic sequences. Our observations lead us to propose that these tandem repeats are actually remnants of ancestral megasatellite repeats, which have split into multiple repeats due to frequent insertions over the course of evolution.

Single-cell transcriptomes provide insights into expansion of glial cells in Bombyx mori

The diversity of cell types in the brain and how these change during different developmental stages,remains largely unknown.The life cycle of insects is short and goes through 4 distinct stages including embryonic,larval,pupal,and adult stages.During postembryonic life,the larval brain transforms into a mature adult version after metamorphosis.The silkworm,Bombyx mori,is a lepidopteran model insect.Here,we characterized the brain cell repertoire of larval and adult B.mori by obtaining 50708 single-cell transcriptomes.Seventeen and 12 cell clusters from larval and adult brains were assigned based on marker genes,respectively.Identified cell types include Kenyon cells,optic lobe cells,monoaminergic neurons,surface glia,and astrocyte glia.We further assessed the cell type compositions of larval and adult brains.We found that the transition from larva to adult resulted in great expansion of glial cells.The glial cell accounted for 49.8%of adult midbrain cells.Compared to flies and ants,the mushroom body kenyon cell is insufficient in B.mori,which accounts for 5.4%and 3.6%in larval and adult brains,respectively.Analysis of neuropeptide expression showed that the abundance and specificity of expression varied among individual neuropeptides.Intriguingly,we found that ion transport peptide was specifically expressed in glial cells of larval and adult brains.The cell atlas dataset provides an important resource to explore cell diversity,neural circuits and genetic profiles.

Single-cell transcriptomes reveal molecular specializations of neuronal cell types in the developing cerebellum

The cerebellum is critical for controlling motor and non-motor functions via cerebellar circuit that is composed of defined cell types, which approximately account for more than half of neurons in mammalsThe molecular mechanisms controlling developmental progression and maturation processes of various cerebellar cell types need systematic investigationHere, we analyzed transcriptome profiles of 21119 single cells of the postnatal mouse cerebellum and identified eight main cell clusters. Functional annotation of differentially expressed genes revealed trajectory hierarchies of granule cells (GCs) at various states and implied roles of mitochondrion and ATPases in the maturation of Purkinje cells (PCs), the sole output cells of the cerebellar cortexFurthermore, we analyzed gene expression patterns and co-expression networks of 28 ataxia risk genes, and found that most of them are related with biological process of mitochondrion and around half of them are enriched in PCs. Our results also suggested core transcription factors that are correlated with interneuron differentiation and characteristics for the expression of secretory proteins in glia cells, which may participate in neuronal modulationThus, this study presents a systematic landscape of cerebellar gene expression in defined cell types and a general gene expression framework for cerebellar development and dysfunction.

Single-cell and spatial omics:exploring hypothalamic heterogeneity

Elucidating the complex dynamic cellular organization in the hypothalamus is critical for understanding its role in coordinating fundamental body functions. Over the past decade, single-cell and spatial omics technologies have significantly evolved, overcoming initial technical challenges in capturing and analyzing individual cells. These high-throughput omics technologies now offer a remarkable opportunity to comprehend the complex spatiotemporal patterns of transcriptional diversity and cell-type characteristics across the entire hypothalamus. Current single-cell and single-nucleus RNA sequencing methods comprehensively quantify gene expression by exploring distinct phenotypes across various subregions of the hypothalamus. However, single-cell/single-nucleus RNA sequencing requires isolating the cell/nuclei from the tissue, potentially resulting in the loss of spatial information concerning neuronal networks. Spatial transcriptomics methods, by bypassing the cell dissociation, can elucidate the intricate spatial organization of neural networks through their imaging and sequencing technologies. In this review, we highlight the applicative value of single-cell and spatial transcriptomics in exploring the complex molecular-genetic diversity of hypothalamic cell types, driven by recent high-throughput achievements.

Spatial transcriptomics combined with single-nucleus RNA sequencing reveals glial cell heterogeneity in the human spinal cord

Glial cells play crucial roles in regulating physiological and pathological functions,including sensation,the response to infection and acute injury,and chronic neurodegenerative disorders.Glial cells include astrocytes,microglia,and oligodendrocytes in the central nervous system,and satellite glial cells and Schwann cells in the peripheral nervous system.Despite the greater understanding of glial cell types and functional heterogeneity achieved through single-cell and single-nucleus RNA sequencing in animal models,few studies have investigated the transcriptomic profiles of glial cells in the human spinal cord.Here,we used high-throughput single-nucleus RNA sequencing and spatial transcriptomics to map the cellular and molecular heterogeneity of astrocytes,microglia,and oligodendrocytes in the human spinal cord.To explore the conservation and divergence across species,we compared these findings with those from mice.In the human spinal cord,astrocytes,microglia,and oligodendrocytes were each divided into six distinct transcriptomic subclusters.In the mouse spinal cord,astrocytes,microglia,and oligodendrocytes were divided into five,four,and five distinct transcriptomic subclusters,respectively.The comparative results revealed substantial heterogeneity in all glial cell types between humans and mice.Additionally,we detected sex differences in gene expression in human spinal cord glial cells.Specifically,in all astrocyte subtypes,the levels of NEAT1 and CHI3L1 were higher in males than in females,whereas the levels of CST3 were lower in males than in females.In all microglial subtypes,all differentially expressed genes were located on the sex chromosomes.In addition to sex-specific gene differences,the levels of MT-ND4,MT2A,MT-ATP6,MT-CO3,MT-ND2,MT-ND3,and MT-CO_(2) in all spinal cord oligodendrocyte subtypes were higher in females than in males.Collectively,the present dataset extensively characterizes glial cell heterogeneity and offers a valuable resource for exploring the cellular basis of spinal cordrelated illnesses,including chronic pain,amyotrophic lateral sclerosis,and multiple sclerosis.

Exosomes originating from neural stem cells undergoing necroptosis participate in cellular communication by inducing TSC2 upregulation of recipient cells following spinal cord injury

We previously demonstrated that inhibiting neural stem cells necroptosis enhances functional recovery after spinal cord injury.While exosomes are recognized as playing a pivotal role in neural stem cells exocrine function,their precise function in spinal cord injury remains unclear.To investigate the role of exosomes generated following neural stem cells necroptosis after spinal cord injury,we conducted singlecell RNA sequencing and validated that neural stem cells originate from ependymal cells and undergo necroptosis in response to spinal cord injury.Subsequently,we established an in vitro necroptosis model using neural stem cells isolated from embryonic mice aged 16-17 days and extracted exosomes.The results showed that necroptosis did not significantly impact the fundamental characteristics or number of exosomes.Transcriptome sequencing of exosomes in necroptosis group identified 108 differentially expressed messenger RNAs,104 long non-coding RNAs,720 circular RNAs,and 14 microRNAs compared with the control group.Construction of a competing endogenous RNA network identified the following hub genes:tuberous sclerosis 2(Tsc2),solute carrier family 16 member 3(Slc16a3),and forkhead box protein P1(Foxp1).Notably,a significant elevation in TSC2 expression was observed in spinal cord tissues following spinal cord injury.TSC2-positive cells were localized around SRY-box transcription factor 2-positive cells within the injury zone.Furthermore,in vitro analysis revealed increased TSC2 expression in exosomal receptor cells compared with other cells.Further assessment of cellular communication following spinal cord injury showed that Tsc2 was involved in ependymal cellular communication at 1 and 3 days post-injury through the epidermal growth factor and midkine signaling pathways.In addition,Slc16a3 participated in cellular communication in ependymal cells at 7 days post-injury via the vascular endothelial growth factor and macrophage migration inhibitory factor signaling pathways.Collectively,these findings confirm that exosomes derived from neural stem cells undergoing necroptosis play an important role in cellular communication after spinal cord injury and induce TSC2 upregulation in recipient cells.

Single-cell transcriptomic profiling reveals ZEB1-mediated regulation in microglial subtypes and the impact of exercise on neuroinflammatory responses

Background:This study aims to identify distinct cellular subtypes within brain tissue using single-cell transcriptomic analysis,focusing on specific biomarkers that differentiate cell types and the effects of traditional and exercise therapy.Methods:Four samples were analyzed:older control(OC),older exercise(OE),younger control(YC),and younger exercise(YE).Single-cell RNA sequencing was used to distinguish cellular subtypes through their biomarker profiles.Data visualization included violin and t-SNE plots to illustrate biomarker expression across cell clusters such as oligodendrocytes,microglia,and astrocytes.Additionally,BV2 cells were exposed to amyloid-beta fragments to simulate Alzheimer’s disease,assessing the impact of exercise-induced cellular responses.Results:Distinct cellular subtypes were identified:oligodendrocytes(MBP,St18),microglia(Dock8),and astrocytes(Aqp4,Gpc5).Sample OE was predominantly oligodendrocytes,while YE had more astrocytes,inhibitory neurons,and Canal-Retzius cells.YC showed a significant presence of Olfm3+ganglion neurons.ZEB1 gene knockout revealed changes in SMAD family gene expression,which regulate ferroptosis.Oxidative stress levels were also evaluated.Conclusion:This profiling enhances our understanding of brain cellular functions and interactions,potentially informing targeted therapies in neurological research.Exercise may influence brain cell immune responses and cell death pathways by regulating specific gene expressions,offering new insights for treating neuroinflammation and degeneration.

Subcutaneous and intramuscular fat transcriptomes show large differences in network organization and associations with adipose traits in pigs

Subcutaneous fat(SCF)and intramuscular fat(IMF)deposition is relevant to health in humans,as well as meat production and quality in pigs.In this study,we generated RNA sequence data for 122 SCF,120 IMF,and 87 longissimus dorsi muscle(LDM)samples using 155 F6 pigs from a specially designed heterogeneous population generated by intercrossing four highly selected European commercial breeds and four indigenous Chinese pig breeds.The phenotypes including waist back fat thickness and intramuscular fat content were also measured in the 155 F6 pigs.We found that the genes in SCF and IMF differed largely in both expression levels and network connectivity,and highlighted network modules that exhibited strongest gain of connectivity in SCF and IMF,containing genes that were associated with the immune process and DNA double-strand repair,respectively.We identified 215 SCF genes related to kinase inhibitor activity,mitochondrial fission,and angiogenesis,and 90 IMF genes related to lipolysis and fat cell differentiation,displayed a tissue-specific association with back fat thickness and IMF content,respectively.We found that cis-expression QTL for trait-associated genes in the two adipose tissues tended to have tissuedependent predictability for the two adipose traits.Alternative splicing of genes was also found to be associated with SCF or IMF deposition,but the association was much less extensive than that based on expression levels.This study provides a better understanding of SCF and IMF gene transcription and network organization and identified critical genes and network modules that displayed tissue-specific associations with subcutaneous and intramuscular fat deposition.These features are helpful for designing breeding programs to genetically improve the two adipose traits in a balanced way.

De novo assembly and comparative analysis of root transcriptomes from different varieties of Panax ginseng C. A. Meyer grown in different environments

Panax ginseng C. A. Meyer is an important traditional herb in eastern Asia. It contains ginsenosides, which are primary bioactive compounds with medicinal properties. Although ginseng has been cultivated since at least the Ming dynasty to increase production, cultivated ginseng has lower quantities of ginsenosides and lower disease resistance than ginseng grown under natural conditions. We extracted root RNA from six varieties of fifth-year P. ginseng cultivars representing four different growth conditions, and performed Illumina paired-end sequencing. In total, 163,165,706 raw reads were obtained and used to generate a de novo transcriptome that consisted of 151,763 contigs(76,336 unigenes), of which 100,648 contigs(66.3%) were successfully annotated. Differential expression analysis revealed that most differentially expressed genes(DEGs) were upregulated(246 out of 258, 95.3%) in ginseng grown under natural conditions compared with that grown under artificial conditions. These DEGs were enriched in gene ontology(GO) terms including response to stimuli and localization. In particular, some key ginsenoside biosynthesis-related genes, including HMG-Co A synthase(HMGS), mevalonate kinase(MVK), and squalene epoxidase(SE), were upregulated in wild-grown ginseng. Moreover, a high proportion of disease resistance-related genes were upregulated in wild-grown ginseng. This study is the first transcriptome analysis to compare wild-grown and cultivated ginseng, and identifies genes that may produce higher ginsenoside content and better disease resistance in the wild; these genes may have the potential to improve cultivated ginseng grown in artificial environments.

Analysis of transcriptomes of three orb-web spider species reveals gene profiles involved in silk and toxin

As an ancient arthropod with a history of 390 million years, spiders evolved numerous morphological forms resulting from adaptation to different environments. The venom and silk of spiders, which have promising commercial applications in agriculture, medicine and engineering fields, are of special interests to researchers. However, little is known about their genomic components, which hinders not only understanding spider biology but also utilizing their valuable genes. Here we report on deep sequenced and de novo assembled transcriptomes of three orb-web spider species, Gasteracantha arcuata, Nasoonaria sinensis and Gasteracantha hasselti which are distributed in tropical forests of south China. With Illumina paired-end RNA-seq technology, 54 871, 101 855 and 75 455 unigenes for the three spider species were obtained, respectively, among which 9 300, 10 001 and 10 494 unique genes are annotated, respectively. From these annotated unigenes, we comprehensively analyzed silk and toxin gene components and structures for the three spider species. Our study provides valuable transcriptome data for three spider species which previously lacked any genetic/genomic data. The results have laid the first fundamental genomic basis for exploiting gene resources from these spiders.

A gene family-based method for interspecies comparisons of sequencing-based transcriptomes and its use in environmental adaptation analysis

We describe a new method for sequencing-based cross-species transcriptome comparisons and define a new metric for evaluating gene expression across species using protein-coding families as units of comparison. Using this measure transcriptomes from different species were evaluated by mapping them to gene families and integrating the mapping results with expression data. Statistical tests were applied to the transcriptome evaluation results to identify differentially expressed families. A Perl program named Pro-Diff was compiled to im- plement this method. To evaluate the method and provide an example of its use, two liver EST transcriptomes from two closely related fish that live in different temperature zones were compared. One EST library was from a recent sequencing project of Dissosticus maw- soni, a fish that lives in cold Antarctic sea waters, while the other was newly sequenced data （available at： http：//www.fishgenome.org/ polarbank/） from Notothenia angustata, a species that lives in temperate near-shore water of southern New Zealand. Results from the com- parison were consistent with results inferred from phenotype differences and also with our previously published Gene Ontology-based method. The Pro-Diffprogram and operation manual can be downloaded from： http：//www.fishgenome.org/download/Prodiff.rar.

High-throughput RNA sequencing reveals differences between the transcriptomes of the five spore forms of Puccinia striiformis f.sp.tritici,the wheat stripe rust pathogen

The devastating wheat stripe(yellow)rust pathogen,Puccinia striiformis f.sp.tritici(Pst),is a macrocyclic and heteroe-cious fungus.Pst produces urediniospores and teliospores on its primary host,wheat,and pycniospores and aeciospores are produced on its alternate hosts,barberry(Berberis spp.)or mahonia(Mahonia spp.).Basidiospores are developed from teliospores and infect alternate hosts.These five spore forms play distinct roles in Pst infection,disease development,and fungal survival,etc.However,the specific genes and mechanisms underlying these functional differences are largely unknown.In this study,we performed,for the first time in rust fungi,the deep RNA sequencing to examine the transcriptomic shift among all five Pst spore forms.Among a total of 29,591 identified transcripts,951 were specifically expressed in basidiospores,whereas 920,761,266,and 110 were specific for teliospores,pycniospores,aeciospores,and urediniospores,respectively.Additionally,transcriptomes of sexual spores,namely pycniospores and basidiospores,showed significant differences from those of asexual spores(urediniospores,teliospores,and aeciospores),and transcriptomes of urediniospores and aeciospores were more similar to each other than to the three other spore forms.Especially,the basidiospores and pycniospores which infected the berberis shows wide differences in the cell wall degrading-enzymes and mating and pheromone response genes.Besides,we also found that there are 6234 differential expressed genes between the urediniospores and pycniospores,while only have 3 genes have alternative splicing enents,suggesting that differential genes expression may make more contribution than AS.This comprehensive transcriptome profiling can substantially improve our understanding of the developmental biology of the wheat stripe rust fungus.