Tissue-specific temperature dependence of RNA editing levels in zebrafish.

BACKGROUND: RNA editing by adenosine deaminase acting on RNA (ADAR) occurs in all metazoans and fulfils several functions. Here, we examined effects of acclimation temperature (27 °C, 18 °C,13 °C) on editing patterns in six tissues of zebrafish (Danio rerio). RESULTS: Sites and total amounts of editing differed among tissues. Brain showed the highest levels, followed by gill and skin. In these highly edited tissues, decreases in temperatures led to large increases in total amounts of editing and changes in specific edited sites. Gene ontology analysis showed both similarities (e.g., endoplasmic reticulum stress response) and differences in editing among tissues. The majority of edited sites were in transcripts of transposable elements and the 3'UTR regions of protein coding genes. By experimental validation, translation efficiency was directly related to extent of editing of the 3'UTR region of an mRNA. CONCLUSIONS: RNA editing increases 3'UTR polymorphism and affects efficiency of translation. Such editing may lead to temperature-adaptive changes in the proteome through altering relative amounts of synthesis of different proteins.

Metagenomics revealing molecular profiles of microbial community structure and metabolic capacity in Bamucuo lake, Tibet.

Microorganisms play critical ecological roles in the global biogeochemical cycles. However, extensive information on the microbial communities in Qinghai-Tibet Plateau (QTP), which is the highest plateau in the world, is still lacking, particularly in high elevation locations above 4500 m. Here, we performed a survey of th e soil and water microbial communities in Bamucuo Lake, Tibet, by using shotgun metagenomic methods. In the soil and water samples, we reconstructed 75 almost complete metagenomic assembly genomes, and 74 of the metagenomic assembly genomes from the water sample represented novel species. Proteobacteria and Actinobacteria were found to be the dominant bacterial phyla, while Euryarchaeota was the dominant archaeal phylum. The largest virus, Pandoravirus salinus, was found in the soil microbial community. We concluded that the microorganisms in Bamucuo Lake are most likely to fix carbon mainly through the 3-hydroxypropionic bi-cycle pathway. This study, for the first time, characterized the microbial community composition and metabolic capacity in QTP high-elevation locations with 4555 m, confirming that QTP is a vast and valuable resource pool, in which many microorganisms can be used to develop new bioactive substances and new antibiotics to which pathogenic microorganisms have not yet developed resistance.

Population genomics of an icefish reveals mechanisms of glacier-driven adaptive radiation in Antarctic notothenioids.

BACKGROUND: Antarctica harbors the bulk of the species diversity of the dominant teleost fish suborder-Notothenioidei. However, the forces that shape their evolution are still under debate. RESULTS: We sequenced the genome of an icefish, Chionodraco hamatus, and used population genomics and demographic modelling of sequenced genomes of 52 C. hamatus individuals collected mainly from two East Antarctic regions to investigate the factors driving speciation. Results revealed four icefish populations with clear reproduction separation were established 15 to 50 kya (kilo years ago) during the last glacial maxima (LGM). Selection sweeps in genes involving immune responses, cardiovascular development, and photoperception occurred differentially among the populations and were correlated with population-specific microbial communities and acquisition of distinct morphological features in the icefish taxa. Population and species-specific antifreeze glycoprotein gene expansion and glacial cycle-paced duplication/degeneration of the zona pellucida protein gene families indicated fluctuating thermal environments and periodic influence of glacial cycles on notothenioid divergence. CONCLUSIONS: We revealed a series of genomic evidence indicating differential adaptation of C. hamatus populations and notothenioid species divergence in the extreme and unique marine environment. We conclude that geographic separation and adaptation to heterogeneous pathogen, oxygen, and light conditions of local habitats, periodically shaped by the glacial cycles, were the key drivers propelling species diversity in Antarctica.

The influence of educational and emotional support on e-learning acceptance: An integration of social support theory and TAM.

Flexible education is considered the primary function of e-learning, however, empirical evidence during the COVID-19 pandemic has also demonstrated that students may seek emotional comforts in e-learning to alleviate their negative emotions. This study aims to provide a holistic view of the antecedents of college students' e-learning acceptance by integrating social support theory with the technology acceptance model. Specifically, drawing upon social support theory, this study adopted perceived educational support and perceived emotional support as two driving factors and examined their influences on students' continuous intention in e-learning. The model was empirically validated using survey data from 512 college respondents in China during the first wave of the pandemic. Our results suggested that while perceived educational support exerts a major influence on e-learning acceptance, perceived emotional support also has an important role to play. Besides, the analytics results suggested that the two facets of support had different influencing patterns: perceived educational support has a positive and significant relationship with both perceived ease of use and perceived usefulness, whereas perceived emotional support solely has a significant relationship with perceived ease of use. Additionally, compared with the prior studies, the effect size ( ß ) between perceived ease of use and perceived usefulness is larger in the present study (COVID-19 context). These findings stress the need to better understand the mechanism by which social support influences college students' e-learning acceptance and to make use of various kinds of social supports to enhance perceived ease of use (e.g. human-computer interface), promote perceived usefulness, and ultimately motivate more students' continuance intention in e-learning.

Specific immunity proteomic profile of the skin mucus of Antarctic fish Chionodraco hamatus and Notothenia coriiceps.

The white-blooded Antarctic icefish is the only known vertebrate lacking oxygen-transporting haemoglobins. Fish skin mucus, as the first line of defence against pathogens, can reflect fish welfare. In this study, we analysed the skin mucus proteome profiles of the two Antarctic fish species, the white-blooded Antarctic icefish, Chionodraco hamatus, and the red-blooded Antarctic fish, Notothenia coriiceps, unfolding the different proteins by liquid chromatography coupled with tandem mass spectrometry isobaric tags for relative and absolute quantitation (iTRAQ) technology. Of the 4444 totally identified proteins, 227 differentially expressed proteins (DEPs) were found in the comparison between C. hamatus and N. coriiceps, of which 121 were upregulated and 106 were downregulated in the icefish. In the Kyoto Encyclopedia of Genes and Genomes pathway annotation, we found two pathways "Legionellosis" and "Complement and coagulation cascades" were significantly enriched, among of which innate immune candidate proteins such as C3, CASP1, ASC, F3 and C9 were significantly upregulated, suggesting their important roles in C. hamatus immune system. Additionally, the DEP protein-protein interaction network analysis and "Response to stress" GO category provided candidate biomarkers for deep understanding of the distinct immune response of the two Antarctic fish underlying the cold adaptation.

Transcriptome profiling analysis of sex-based differentially expressed mRNAs and lncRNAs in the brains of mature zebrafish (Danio rerio).

BACKGROUND: Similar to humans, the zebrafish brain plays a central role in regulating sexual reproduction, maturation and sexual behavior. However, systematic studies of the dimorphic patterns of gene expression in the brain of male and female zebrafish are lacking. RESULTS: In this study, the mRNA and lncRNA expression profiles were obtained from the brain tissue samples of the three male and three female zebrafish by high-throughput transcriptome sequencing. We identified a total of 108 mRNAs and 50 lncRNAs with sex-based differential expression. We randomly selected four differentially expressed genes for RT-qPCR verification and the results certified that the expression pattern showed a similar trend between RNA-seq and RT-qPCR results. Protein-protein interaction network analysis, Gene Ontology (GO) analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed to obtain the biological significance of differentially expressed mRNA in the brain dimorphism of zebrafish. Finally, a Pearson correlation analysis was performed to construct the co-expression network of the mRNAs and lncRNAs. CONCLUSIONS: We found that 12 new lncRNAs not only have significant gender specificity in the brain of zebrafish, and this finding may provide a clue to further study of the functional difference between male and female zebrafish brain.

GC bias lead to increased small amino acids and random coils of proteins in cold-water fishes.

BACKGROUND: Temperature adaptation of biological molecules is fundamental in evolutionary studies but remains unsolved. Fishes living in cold water are adapted to low temperatures through adaptive modification of their biological molecules, which enables their functioning in extreme cold. To study nucleotide and amino acid preference in cold-water fishes, we investigated the substitution asymmetry of codons and amino acids in protein-coding DNA sequences between cold-water fishes and tropical fishes., The former includes two Antarctic fishes, Dissostichus mawsoni (Antarctic toothfish), Gymnodraco acuticeps (Antarctic dragonfish), and two temperate fishes, Gadus morhua (Atlantic cod) and Gasterosteus aculeatus (stickleback), and the latter includes three tropical fishes, including Danio rerio (zebrafish), Oreochromis niloticus (Nile tilapia) and Xiphophorus maculatus (Platyfish). RESULTS: Cold-water fishes showed preference for Guanines and cytosines (GCs) in both synonymous and nonsynonymous codon substitution when compared with tropical fishes. Amino acids coded by GC-rich codons are favored in the temperate fishes, while those coded by AT-rich codons are disfavored. Similar trends were discovered in Antarctic fishes but were statistically weaker. The preference of GC rich codons in nonsynonymous substitution tends to increase ratio of small amino acid in proteins, which was demonstrated by biased small amino acid substitutions in the cold-water species when compared with the tropical species, especially in the temperate species. Prediction and comparison of secondary structure of the proteomes showed that frequency of random coils are significantly larger in the cold-water fish proteomes than those of the tropical fishes. CONCLUSIONS: Our results suggested that natural selection in cold temperature might favor biased GC content in the coding DNA sequences, which lead to increased frequency of small amino acids and consequently increased random coils in the proteomes of cold-water fishes.

Evolutionary suppression of erythropoiesis via the modulation of TGF-ß signalling in an Antarctic icefish.

The Antarctic icefish, a family (Channichthyidae) of teleosts within the perciform suborder Notothenioidei, are the only known vertebrates without oxygen-transporting haemoglobins and that are largely devoid of circulating erythrocytes. To elucidate the evo-devo mechanisms underpinning the suppressed erythropoiesis in the icefish, we conducted comparative studies on the transcriptomes and microRNAomes of the primary haematopoietic tissues between an icefish (Chionodraco hamatus) and two red-blooded notothenioids (Trematomus bernacchii and Gymnodraco acuticeps). We identified substantial remodelling of the haematopoietic programs in the icefish through which erythropoiesis is selectively suppressed. Experimental verification showed that erythropoietic suppression in the icefish may be attributable to the upregulation of TGF-ß signalling, which coincides with reductions in multiple transcription factors essential for erythropoiesis and the upregulation of hundreds of microRNAs, the majority (> 80%) of which potentially target erythropoiesis regulating factors. Of the six microRNAs selected for verification, three miRNAs (miR-152, miR-1388 and miR-16b) demonstrated suppressive functions on GATA1 and ALAS2, which are two factors important for erythroid differentiation, resulting in reduced numbers of erythroids in microinjected zebra fish embryos. Codon substitution analyses of the genes of the TGF-ß superfamily revealed signs of positive selection in TGF-ß1 and endoglin in the lineages leading to Antarctic notothenioids. Both genes are previously known to function in erythropoietic suppression. These findings implied a general trend of erythropoietic suppression in the cold-adapted notothenioid lineages through evolutionary modulation of the multi-functional TGF-ß signalling pathway. This trend is more pronounced in the haemoglobin-less icefish, which may pre-emptively hinder the otherwise defective erythroids from production.

Deletion of Asb15b gene can lead to a significant decrease in zebrafish intermuscular bone.

Intermuscular bones, which are present in numerous economically significant fish species, have a negative impact on the development of aquaculture. The Asb15b gene, primarily expressed in skeletal muscle, plays a crucial role in regulating protein turnover and the development of muscle fibers. It stimulates protein synthesis and controls the differentiation of muscle fibers. In this study, we employed CRISPR/Cas9 technology to generate homozygous zebrafish strains with 7 bp and 49 bp deletions in the Asb15b gene. Subsequent analyses using skeleton staining demonstrated a substantial reduction in the number of intermuscular bones in adult Asb15b-/- -7 bp and Asb15b-/- -49 bp mutants compared to the wild-type zebrafish, with decreases of 30 % (P < 0.001) and 40 % (P < 0.0001), respectively. Histological experiments further revealed that the diameter and number of muscle fibers in adult Asb15b-/- mutants did not exhibit significant changes when compared to wild-type zebrafish. Moreover, qRT-PCR experiments demonstrated significant differences in the expression of bmp6 and runx2b genes, which are key regulators of intermuscular bone development, during different stages of intermuscular bone development in Asb15b-/- mutants. This study strongly suggests that the Asb15b gene plays a crucial role in regulating intermuscular bone development in fish and lays the groundwork for further exploration of the role of the Asb15b gene in zebrafish intermuscular bone development.

Identification of two miRNAs regulating cardiomyocyte proliferation in an Antarctic icefish.

The hemoglobinless Antarctic icefish develop large hearts to compensate for reduced oxygen-carrying capacity, which serves as a naturally occurred model to explore the factors regulating cardiogenesis. Through miRNAome and microRNAome comparisons between an icefish (Chionodraco hamatus) and two red-blooded notothenioids, we discovered significant upregulation of factors in the BMP signaling pathways and altered expression of many miRNAs, including downregulation of 14 miRNAs in the icefish heart. Through knocking down of these miRNAs, we identified two of them, miR-458-3p and miR-144-5p, involved in enlarged heart development. The two miRNAs were found to regulate cardiomyocyte proliferation by targeting bone morphogenetic protein-2 (bmp2). We further validated that activation of the miRNA-bmp2 signaling in the fish heart could be triggered by hypoxic exposure. Our study suggested that a few miRNAs play important roles in the hypoxia-induced cardiac remodeling of the icefish which shed new light on the mechanisms regulating cardiomyocyte proliferation in heart.

Genome sequencing of Coryphaenoides yaquinae reveals convergent and lineage-specific molecular evolution in deep-sea adaptation.

Abyssal (3501-6500 m) and hadal (>6500 m) fauna evolve under harsh abiotic stresses, characterized by high hydrostatic pressure, darkness and food shortage, providing unique opportunities to investigate mechanisms underlying environmental adaptation. Genomes of several hadal species have recently been reported. However, the genetic adaptation of deep sea species across a broad spectrum of ocean depths has yet to be thoroughly investigated, due to the challenges imposed by collecting the deep sea species. To elucidate the correlation between genetic innovation and vertical distribution, we generated a chromosome-level genome assembly of the macrourids Coryphaenoides yaquinae, which is widely distributed in the abyssal/hadal zone ranging from 3655 to 7259 m in depth. Genomic comparisons among shallow, abyssal and hadal-living species identified idiosyncratic and convergent genetic alterations underlying the extraordinary adaptations of deep-sea species including light perception, circadian regulation, hydrostatic pressure and hunger tolerance. The deep-sea fishes (Coryphaenoides Sp. and Pseudoliparis swirei) venturing into various ocean depths independently have undergone convergent amino acid substitutions in multiple proteins such as rhodopsin 1, pancreatic and duodenal homeobox 1 and melanocortin 4 receptor which are known or verified in zebrafish to be related with vision adaptation and energy expenditure. Convergent evolution events were also identified in heat shock protein 90 beta family member 1 and valosin-containing protein genes known to be related to hydrostatic pressure adaptation specifically in fishes found around the hadal range. The uncovering of the molecular convergence among the deep-sea species shed new light on the common genetic innovations required for deep-sea adaptation by the fishes.

Morphological and molecular evolution of hadal amphipod's eggs provides insights into embryogenesis under high hydrostatic pressure.

Hadal zones are unique habitats characterized by high hydrostatic pressure (HHP) and scarce food supplies. The ability of eggs of species dwelling in hadal zones to develop into normal embryo under high hydrostatic pressure is an important evolutionary and developmental trait. However, the mechanisms underlying the development of eggs of hadal-dwelling species remain unknown due to the difficulty of sampling ovigerous females. Here, morphological and transcriptome analyses of eggs of the "supergiant" amphipod Alicella gigantea collected from the New Britain Trench were conducted. The morphology of A. gigantea eggs, including size, was assessed and the ultrastructure of the eggshell was investigated by scanning electron microscopy. Transcriptome sequencing and molecular adaptive evolution analysis of A. gigantea eggs showed that, as compared with shallow-water Gammarus species, genes exhibiting accelerated evolution and the positively selected genes were mostly related to pathways associated with "mitosis" and "chitin-based embryonic cuticle biosynthetic process", suggesting that "normal mitosis maintenance" and "cuticle development and protection" are the two main adaptation strategies for survival of eggs in hadal environments. In addition, the concentration of trimethylamine oxide (TMAO), an important osmotic regulator, was significantly higher in the eggs of hadal amphipods as compared to those of shallow-water species, which might promote the eggs' adaptation abilities. Morphological identification, evolutionary analysis, and the trimethylamine oxide concentration of A. gigantea eggs will facilitate a comprehensive overview of the piezophilic adaptation of embryos in hadal environments and provide a strategy to analyze embryogenesis under high hydrostatic pressure.

Trace Elemental Analysis of the Exoskeleton, Leg Muscle, and Gut of Three Hadal Amphipods.

Hadal trenches are the deepest areas worldwide. Amphipods are considered a key factor in hadal ecosystems because of their important impacts on the hadal environment. Amphipods have benthic habits, and therefore, serve as good metal biomonitors. However, little is known about the hadal amphipod metal accumulations. In the present study, Alicella gigantea, Hirondellea gigas, and Scopelocheirus schellenbergi were sampled from the New Britain Trench (8824m, 7.02S 149.16E), Mariana Trench (10,839m, 11.38N 142.42E), and Marceau Trench (6690m, 1.42N 148.74E) in the West Pacific Ocean, respectively. The elemental concentrations of the three hadal amphipods were subsequently investigated. Nine trace elements (V, Cr, Mn, Co, Ni, Se, Mo, Ag, and Cd) of three tissues (exoskeleton, leg muscle, and gut) of the hadal amphipods were detected by using inductively coupled plasma mass spectrometry (ICP-MS) method. The concentrations of Cr, Cd, and Mn were comparably higher among those nine examined elements. The greatest accumulations of the elements Cr, Ag, and V in the exoskeleton and leg muscle were observed in H. gigas, and elements Mn, Co, and Se showed the highest accumulations in the gut in H. gigas among the three hadal amphipods. In addition, comparisons of the leg muscle trace element accumulation between the hadal amphipods and non-abyssal and shallow water decapoda and amphipoda species showed that the hadal amphipods possessed comparably higher concentrations of the trace elements Cd, Co, Mo, Ag, and V. This finding suggested a bottom-up effect of food availability and indicated the effects of human activities within the hadal environments. This study reveals the trace element bio-accumulation of three hadal amphipods, and suggests that deep-sea amphipods are potential indicator species for trace element bioavailability in the deep-sea environment.

Identification and characterization of circRNAs as competing endogenous RNAs for miRNA-mRNA in colorectal cancer.

BACKGROUND: Recent studies showed that circRNAs are involved in the biological process of some human cancers. However, little is known about their functions in colorectal cancer (CRC). METHODS: Here we first revealed the expression profiles of circRNAs in the CRC tissues and the adjacent non-tumorous tissues using high-throughput sequencing. The sequence feature, chromosome location, alternative splicing and other characteristics of the circRNAs were also explored. The miRNA and mRNA expression profiles were then obtained by analyzing relevant CRC data retrived from the TCGA database. We obtained and analyzed the competing endogenous RNA (ceRNA) network of the top three pairs of the largest up-regulated and down-regulated circRNAs. RESULTS: In this study, we obtained 50,410 circRNAs in the CRC tissue and the adjacent non-tumor tissues, of which 33.7% (16,975) were new, and revealed differential changes in circRNA expression during colorectal carcinogenesis. We have identified six potential key circRNAs (circPIEZO1-3, hsa_circ_0067163, hsa_circ_0140188, hsa_circ_0002632, hsa_circ_0001998 and hsa_circ_0023990) associated with CRC, which play important roles in carcinogenesis as ceRNA for regulation of miRNA-mRNA network. In the subsequent KEGG analysis, several CRC-related pathways were found. CONCLUSIONS: Our findings advance the understanding of the pathogenesis of CRC from the perspective of circRNAs and provide some circRNAs as candidate diagnostic biomarkers or potential therapeutic targets.

The genomic basis for colonizing the freezing Southern Ocean revealed by Antarctic toothfish and Patagonian robalo genomes.

BACKGROUND: The Southern Ocean is the coldest ocean on Earth but a hot spot of evolution. The bottom-dwelling Eocene ancestor of Antarctic notothenioid fishes survived polar marine glaciation and underwent adaptive radiation, forming >120 species that fill all water column niches today. Genome-wide changes enabling physiological adaptations and the rapid expansion of the Antarctic notothenioids remain poorly understood. RESULTS: We sequenced and compared 2 notothenioid genomes-the cold-adapted and neutrally buoyant Antarctic toothfish Dissostichus mawsoni and the basal Patagonian robalo Eleginops maclovinus, representing the temperate ancestor. We detected >200 protein gene families that had expanded and thousands of genes that had evolved faster in the toothfish, with diverse cold-relevant functions including stress response, lipid metabolism, protein homeostasis, and freeze resistance. Besides antifreeze glycoprotein, an eggshell protein had functionally diversified to aid in cellular freezing resistance. Genomic and transcriptomic comparisons revealed proliferation of selcys-transfer RNA genes and broad transcriptional upregulation across anti-oxidative selenoproteins, signifying their prominent role in mitigating oxidative stress in the oxygen-rich Southern Ocean. We found expansion of transposable elements, temporally correlated to Antarctic notothenioid diversification. Additionally, the toothfish exhibited remarkable shifts in genetic programs towards enhanced fat cell differentiation and lipid storage, and promotion of chondrogenesis while inhibiting osteogenesis in bone development, collectively contributing to the achievement of neutral buoyancy and pelagicism. CONCLUSIONS: Our study revealed a comprehensive landscape of evolutionary changes essential for Antarctic notothenioid cold adaptation and ecological expansion. The 2 genomes are valuable resources for further exploration of mechanisms underlying the spectacular notothenioid radiation in the coldest marine environment.

Transcriptome comparison reveals a genetic network regulating the lower temperature limit in fish.

Transcriptional plasticity is a major driver of phenotypic differences between species. The lower temperature limit (LTL), namely the lower end of survival temperature, is an important trait delimiting the geographical distribution of a species, however, the genetic mechanisms are poorly understood. We investigated the inter-species transcriptional diversification in cold responses between zebrafish Danio rerio and tilapia Oreochromis niloticus, which were reared at a common temperature (28 °C) but have distinct LTLs. We identified significant expressional divergence between the two species in the orthologous genes from gills when the temperature cooled to the LTL of tilapia (8 °C). Five KEGG pathways were found sequentially over-represented in the zebrafish/tilapia divergently expressed genes in the duration (12 hour) of 8 °C exposure, forming a signaling cascade from metabolic regulation to apoptosis via FoxO signaling. Consistently, we found differential progression of apoptosis in the gills of the two species in which zebrafish manifested a delayed and milder apoptotic phenotype than tilapia, corresponding with a lower LTL of zebrafish. We identified diverged expression in 25 apoptosis-related transcription factors between the two species which forms an interacting network with diverged factors involving the FoxO signaling and metabolic regulation. We propose a genetic network which regulates LTL in fishes.

Identification of Genetic Mutations in Human Lung Cancer by Targeted Sequencing.

Lung cancer remains the most prevalent malignancy and the primary cause of cancer-related deaths worldwide. Unique mutations patterns can be found in lung cancer subtypes, in individual cancers, or within a single tumor, and drugs that target these genetic mutations and signal transduction pathways are often beneficial to patients. In this study, we used the Ion Torrent AmpliSeq Cancer Panel to sequence 737 loci from 45 cancer-related genes and oncogenes to identify genetic mutations in 48 formalin-fixed, paraffin-embedded (FFPE) human lung cancer samples from Chinese patients. We found frequent mutations in EGFR, KRAS, PIK3CA, and TP53 genes. Moreover, we observed that a portion of the lung cancer samples harbored two or more mutations in these key genes. This study demonstrates the feasibility of using the Ion Torrent sequencing to efficiently identify genetic mutations in individual tumors for targeted lung cancer therapy.

Frequent KIT mutations in human gastrointestinal stromal tumors.

Identifying gene mutations in individual tumors is critical to improve the efficacy of cancer therapy by matching targeted drugs to specific mutations. Gastrointestinal stromal tumors (GIST) are stromal or mesenchymal subepithelial neoplasms affecting the gastrointestinal tract and frequently contain activating gene mutations in either KIT or platelet-derived growth factor A (PDGFRA). Although GIST is highly responsive to several selective tyrosine kinase inhibitors, combined use of inhibitors targeting other mutations is needed to further prolong survival in patients with GIST. In this study, we aim to screen and identify genetic mutations in GIST for targeted therapy using the new Ion Torrent next-generation sequencing platform. Utilizing the Ion Ampliseq Cancer Panel, we sequenced 737 loci from 45 cancer-related genes using DNA extracted from formalin-fixed and paraffin-embedded (FFPE) samples of 121 human gastrointestinal stromal tumors, set up stringent parameters for reliable variant calling by filtering out potential raw base calling errors, and identified frequent mutations in the KIT gene. This study demonstrates the utility of using Ion Torrent sequencing to efficiently identify human cancer mutations. This may provide a molecular basis for clinically developing new drugs targeting these gene mutations for GIST therapy.

Genetic mutation analysis of human gastric adenocarcinomas using ion torrent sequencing platform.

Gastric cancer is the one of the major causes of cancer-related death, especially in Asia. Gastric adenocarcinoma, the most common type of gastric cancer, is heterogeneous and its incidence and cause varies widely with geographical regions, gender, ethnicity, and diet. Since unique mutations have been observed in individual human cancer samples, identification and characterization of the molecular alterations underlying individual gastric adenocarcinomas is a critical step for developing more effective, personalized therapies. Until recently, identifying genetic mutations on an individual basis by DNA sequencing remained a daunting task. Recent advances in new next-generation DNA sequencing technologies, such as the semiconductor-based Ion Torrent sequencing platform, makes DNA sequencing cheaper, faster, and more reliable. In this study, we aim to identify genetic mutations in the genes which are targeted by drugs in clinical use or are under development in individual human gastric adenocarcinoma samples using Ion Torrent sequencing. We sequenced 737 loci from 45 cancer-related genes in 238 human gastric adenocarcinoma samples using the Ion Torrent Ampliseq Cancer Panel. The sequencing analysis revealed a high occurrence of mutations along the TP53 locus (9.7%) in our sample set. Thus, this study indicates the utility of a cost and time efficient tool such as Ion Torrent sequencing to screen cancer mutations for the development of personalized cancer therapy.