Search Results (530)

This study investigates the genetic diversity and population structure of Castanopsis tribuloides, a vital tree species in Asian forest ecosystems. Understanding the genetic patterns of keystone forest species provides critical insights into forest resilience and ecosystem function and informs conservation strategies. We analyzed population samples collected from three distinct locations within Doi Suthep Mountain in northern Thailand using Short Tandem Repeat (STR) markers to assess both intra- and inter-population genetic relationships. DNA was extracted from leaf samples and analyzed using a panel of polymorphic microsatellite loci specifically optimized for Castanopsis species. Statistical analyses included the assessment of forensic parameters (number of alleles, observed and expected heterozygosity, gene diversity, polymorphic information content), population differentiation metrics (G_ST), inbreeding coefficients (F_IS), and gene flow estimates (N_m). We further examined population history through bottleneck analysis using three models (IAM, SMM, and TPM) and visualized genetic relationships through principal coordinate analysis and cluster analysis. Our results revealed significant patterns of genetic structuring across the sampled populations, with genetic distance metrics showing statistically significant differentiation between certain population pairs. The PCA and cluster analyses confirmed distinct population groupings that correspond to geographic distribution patterns. These findings provide the first comprehensive assessment of C. tribuloides population genetics in this region, establishing baseline data for monitoring genetic diversity and informing conservation strategies. This research contributes to our understanding of how landscape features and ecological factors shape genetic diversity patterns in essential forest tree species, with implications for managing forest genetic resources in the face of environmental change. Full article

Background: Anti-EGFR therapy, combined with chemotherapy, represents the standard therapeutic approach for triple wild-type (KRAS/NRAS and BRAF), left-sided, microsatellite stable (MSS) metastatic colorectal cancer (mCRC). However, acquired resistance develops in approximately 50% of patients. This study evaluated the efficacy of anti-EGFR therapy re-challenge and analyzed circulating tumor DNA (ctDNA) for potential resistance mechanisms. Methods: Eleven patients with triple wild-type, MSS, HER2-negative, left-sided mCRC were included. All patients received Cetuximab with chemotherapy as the first-line treatment, with three patients subsequently receiving Cetuximab re-challenge. Twenty-one plasma samples were collected at baseline and at each response assessment for retrospective ctDNA analysis using next-generation sequencing with a 16-gene panel. Results: Genetic alterations were detected in only 14.2% of ctDNA samples. In one re-challenge patient, the KRAS: c.35G>A mutation appeared during progression. No RAS mutations were identified in four patients who progressed on first-line Cetuximab treatment. Conclusions: This preliminary study suggests that clinically based anti-EGFR re-challenge may benefit selected mCRC patients. The low detection rate of resistance-conferring mutations indicates potential alternative resistance mechanisms beyond RAS pathway alterations. Our findings, while limited by sample size and the retrospective design of ctDNA testing, contribute to the growing evidence supporting anti-EGFR re-challenge strategies in mCRC management. Full article

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis; YFP) is the only freshwater cetacean species that remains in the Yangtze River, China. Poyang Lake is connected to the main stream of the Yangtze River, and the number of YFPs in Poyang Lake constitutes approximately half of the total species population. To implement effective conservation measures and formulate scientific genetic management strategies for the YFPs in Poyang Lake, we conducted population genetic analyses on 125 blood samples from the Poyang population and 46 tissue samples from the Anqing population, utilizing mitochondrial DNA D-loop and microsatellite loci. The genetic diversity analysis revealed two haplotypes in the Poyang population, with mitochondrial genetic diversity indices of Hd = 0.481 ± 0.020 and Pi = 0.00078 ± 0.00030. Microsatellite markers further demonstrated indices of Ho = 0.610 and He = 0.655. The genetic differentiation analysis indicated that the two populations exhibited moderate genetic differentiation (0.05 < Fst < 0.15). Upon excluding the dead samples from the Anqing population, the genetic differentiation between the two populations increased and the gene flow diminished. This indicated that certain dead samples from the Anqing population might have originated from Poyang Lake or had a background of Poyang Lake–Yangtze River migration and gene exchange. This finding was further corroborated by STRUCTURE analysis, which revealed genetic admixture between the two populations. We assessed the current genetic diversity of the Poyang population and its genetic differentiation from the Anqing population. This study provides fundamental data for formulating a conservation program for YFPs in Poyang Lake. Full article

Locally advanced rectal cancer treatment has shifted toward personalized, risk-adapted strategies that balance oncologic control with functional preservation while minimizing toxicity. A multidisciplinary team approach is essential, tailoring treatment guided by individual patient risk factors and priorities. Traditional neoadjuvant chemoradiation and subsequent total mesorectal excision has improved local control, but concerns remain regarding systemic failure and treatment-related morbidity. Total neoadjuvant therapy is now widely considered a preferred approach for more advanced tumors, enhancing systemic control, improving chemotherapy compliance, and facilitating organ preservation in select patients. Recent studies highlight that response-based treatment adaptation allows for better patient stratification, with selected patients who respond well to preoperative chemotherapy potentially omitting radiation without compromising outcomes and omitting surgery for patients with complete clinical responses to chemoradiation and chemotherapy. Advances in molecular profiling, particularly in mismatch repair deficiency or microsatellite instability-high tumors, have enabled the implementation of immune checkpoint inhibitors, permitting select patients to avoid both radiation and surgery, thereby reducing treatment-related toxicities. Future research should focus on validating predictive biomarkers, such as circulating tumor DNA, refining patient selection, and optimizing treatment monitoring while also developing novel therapeutic strategies to further personalize locally advanced rectal cancer management. Full article

Methods: We retrospectively and cross-sectionally reviewed the cases of 648 patients with a histological diagnosis of colon adenocarcinoma. Of these, 166 had partial molecular studies, and 42 cases were selected based on the availability of the genetic markers targeted in this study. We analyzed the frequency of mutations in these genes, as well as their correlation with microsatellite instability (MSI). Results: A high mutation rate was found in the KRAS gene (52.4%). NRAS mutations were less frequent (8.9%), whereas BRAF mutations were observed in 20.8% of cases. This allowed us to identify a patient subgroup with MSI, representing 12.1% of cases. Among the 42 patients analyzed for KRAS, NRAS, BRAF, and MSI mutations, a significant association was observed between KRAS mutations and microsatellite stability, while no association was found between NRAS mutations and MSI. BRAF mutations showed a statistically significant association with MSI (p < 0.05), with the most common mutation being c.1799T > A, p.Val600Glu. The objective of this study is to demonstrate that the NGS-based method for evaluating MSI is rigorously valid compared to the results obtained using IHC and PCR. Conclusions: Comprehensive NGS profiling from the start improves diagnostic efficiency by saving time, tissue, and costs compared to gene-by-gene analysis. It also enables better molecular characterization and facilitates tailored therapeutic strategies, particularly in identifying candidates for targeted therapy and immunotherapy. This approach supports efficient tumor classification based on using KRAS, BRAF, NTRK, ERBB2, and PIK3CA as key markers, along with MSI status. We recommend that, if initial NGS is not feasible, start with KRAS analysis, then test BRAF and MSI if no mutation is found. Full article

In the era of precision oncology, comprehensive molecular profiling is critical for guiding targeted and immunotherapy strategies. This study presents the analytical and clinical validation of a 1021-gene next-generation sequencing (NGS) panel, designed for use with both formalin-fixed paraffin-embedded (FFPE) tissue- and liquid-biopsy specimens. Analytical validation confirmed the assay’s high sensitivity and specificity across variant types—including SNVs (Single Nucleotide Variations), indels, CNVs (Copy Number Variations), and fusions—down to a 0.5% variant allele frequency. The assay also accurately identified microsatellite instability (MSI) and tumor mutational burden (TMB), essential biomarkers for immunotherapy. Clinical validation was performed on over 1300 solid tumor samples from diverse histologies, revealing actionable alterations in over 50% of cases. The panel detected on-label treatment biomarkers in 12.57% of patients, increasing to 20.15% when immunotherapy markers were included. Additionally, the assay demonstrated strong concordance with orthogonal methods and was effective in detecting variants in plasma-derived circulating tumor DNA in 70% of evaluable cases. These findings support the robust performance and broad clinical applicability of the 1021-gene panel for comprehensive genomic profiling in both tissue and liquid biopsies, offering a valuable tool for personalized cancer treatment. Full article

Background: Colorectal cancer (CRC) remains one of the most prevalent and fatal malignancies globally, with radiotherapy playing a crucial role in the treatment of locally advanced rectal cancer (LARC). However, the efficacy of radiotherapy is limited by significant resistance, with only a small proportion of patients achieving a pathologic complete response (PCR) to neoadjuvant chemoradiotherapy (nCRT). This study aims to uncover the genetic and molecular factors contributing to radiotherapy resistance in CRC through an integrated analysis of germline mutations, transcriptomic data, and immune microenvironment characteristics. Methods: Whole-exome sequencing (WES) was performed on tumor samples from 12 LARC patients. Transcriptomic data from the TCGA-READ and GSE150082 (LARC with chemoradiotherapy) cohorts were integrated with WES findings. The independent cohort GSE190826 (neoadjuvant therapy in rectal cancer) dataset was utilized to validate the WES data. Single-cell RNA sequencing (scRNA-seq) analysis of GSE132465 (primary CRC) resolved cellular heterogeneity. A random forest algorithm was employed to develop a predictive gene signature. Results: Our findings reveal a mutational landscape associated with radiotherapy resistance, identifying specific germline mutations linked to treatment outcomes. Differential gene expression analysis highlighted pathways involved in DNA replication, DNA repair, and immune regulation, with a focus on the tumor immune microenvironment (TIME). A gene signature, including CDCA4, FANCA, PBRM1, RPL13, and C12orf43, was developed to predict radiotherapy response. Notably, CDCA4 expression was significantly associated with tumor mutation burden (TMB) and microsatellite instability (MSI), and it plays a crucial role in regulating B cell infiltration in the tumor microenvironment. Conclusions: Our study provides novel insights into the molecular mechanisms of radiotherapy resistance in CRC and proposes CDCA4 and B cell-related immune features as potential biomarkers for patient stratification and personalized treatment strategies. Full article

Background/Objectives: The genus Vitis comprises approximately 70 species with high genetic diversity, among which Vitis vinifera is the most economically significant. Despite numerous studies on the genetic characterizations of V. vinifera, selecting optimal chloroplast DNA barcoding regions for intraspecific differentiation remains unresolved. Most studies have focused on nuclear markers (SSRs, SNPs) or widely used chloroplast loci (e.g., matk, rbcl), which have shown limited resolution at the subspecies level. In this study, the complete chloroplast genomes of 34 V. vinifera accessions from different varieties and hybrids (vinifera, sylvestris, caucasica, and labrusca) were analyzed to identify the key genomic regions for DNA barcoding. Methods: Using bioinformatics tools, we assessed the genome structure, nucleotide variability, microsatellites, codon usage bias, and phylogenetic relationships among the investigated varieties. Results: The chloroplast genomes displayed a quadripartite structure, with lengths ranging from 160,906 to 160,929 bp and a guanine–cytosine (GC) content of ~37.4%. Phylogenetic analysis revealed an unusual position for VV-5 vini and VVVL-3 lab, suggesting potential taxonomic misclassification or hybridization effects. A single locus showed low discrimination power, but the concatenation of five loci (ccsA-trnN-GUU, rpl16, rpl2-rps19, rpoC2, and trnM-CAU) exhibited significantly improved resolution (44.11% K2P), surpassing traditional markers. Conclusions: This study addresses the gap in the literature regarding the use of concatenated chloroplast loci for subspecies research; the results validate these markers across a broader range of Vitis accessions and integrate nuclear and mitochondrial data to achieve a more comprehensive understanding of the evolutionary history and genetic diversity of V. vinifera. Full article

Colorectal cancer (CRC) remains a major health burden in Japan, with precision medicine playing an increasingly critical role in treatment optimization. Key biomarkers, including RAS, BRAF, microsatellite instability/mismatch repair, and human epidermal growth factor receptor 2, can be used as a guide for molecularly targeted therapies and immunotherapy. Advances in molecular diagnostics, including comprehensive genomic profiling, have enabled more precise treatment selection such as RET and NTRK fusions. Nationwide initiatives, such as c-CAT and SCRUM-Japan, can leverage real-world data to refine clinical strategies. Recent developments in circulating tumor DNA analysis have led to novel approaches for minimal residual disease monitoring, as demonstrated by the CIRCULATE-Japan GALAXY study. However, certain challenges persist, including the time required for genetic testing, the limited availability of targeted therapies, and disparities in access to molecular tumor boards. This review summarizes the current landscape of precision medicine in CRC in Japan, emphasizing key biomarkers, genetic testing strategies, targeted therapies, and emerging technologies. Future research should focus on expanding clinical trial access, accelerating drug approvals, and integrating real-world data into clinical practice to further advance precision medicine. Full article

Oncomelania hupensis quadrasi is the intermediate host of S. japonicum, the causative species of schistosomiasis in the Philippines. Conventionally, risk areas are identified by procedures requiring highly skilled personnel and constant surveillance efforts. Recent developments in disease diagnostics explore the utilization of environmental DNA as targets for polymerase chain reactions in disease surveillance. In this study, a low-cost, specific, and efficient SYBR Green-based real-time PCR assay to detect O. h. quadrasi DNA from water samples was developed, optimized, and validated. Primers were designed based on the A18 microsatellite region of O. h. quadrasi. The assay exhibited a detection limit of one copy number per microliter at 99.4% efficiency and R² = 0.999, which specifically amplified O. h. quadrasi DNA only. Validation of this assay in environmental water samples demonstrated 100% PPV and NPV values, suggesting its potential as a tool for identifying risk areas, pathogen-directed surveillance, policy making, and disease control. Full article

Background: Studies on somatic mutations in cancer typically report single-nucleotide variants in coding regions, while mutations in short tandem repeats (STRs) are usually overlooked. Homopolymeric regions, a subset of STRs, are stretches of DNA where only a single nucleotide is repeated multiple times (e.g., AAAAA or TTTTT). Only recently have mutations in such STR regions been seen in colorectal cancer, where microsatellite instability (MSI) is common. In non-melanoma skin cancer (NMSC), MSI is rare. In this study, we focus on somatic mutations in such homopolymeric regions in NMSC and their functional implications. Methods: We performed targeted DNA sequencing (paired tissue and blood from the same individual), using more than 400 cancer-related genes from 32 NMSC patients as cases and non-lesional skin tissue from 16 independent individuals as controls. Results: We identified NMSC-associated STR somatic mutations. These are associated with the dysregulation of DNA damage and repair mechanisms. In artificial intelligence (AI) predictive modeling, these markers could successfully differentiate basal cell carcinoma (BCC) and non-lesional skin tissue. To our knowledge, we present the first study focusing on STR somatic mutations in multiple cancer-related genes in NMSC found only in tumor tissue and not in non-lesional skin tissue. Some of them (APC, BRAF) are associated with more pronounced dysregulation of relevant gene pathways (hedgehog, Notch signaling, and Wnt signaling). Conclusions: Our findings suggest that this STR somatic mutation status might potentially be used to select BCC patients who could benefit from certain precision therapy including hedgehog inhibitors, gamma-secretase inhibitors, anti-Vasuclar endothelial growth factor (VEGF), proteasome inhibitors, and immune check-point inhibitors. Full article

Artificial gynogenesis is an effective means of producing pure lines and is widely used for genetic analysis of fish and for sex control. In this study, inactivated sperm from heterogenous blunt snout bream (Megalobrama amblycephala, MA) were used to activate Kohaku koi (Cyprinus carpio var. koi, CK) and produce high-quality female offspring. To determine whether the offspring were gynogenetic fish, the karyotype and DNA content of the CK, MA and the induced offspring (IO) were first compared and it was found that the IO were diploid with 100 chromosomes and their karyotype was 22m + 34sm + 22st + 22t. The DNA content of the IO was not significantly different from that of the CK. Subsequently, the amplified band profiles of CK, MA and IO were analyzed with species-specific microsatellite markers. The results showed that there were no amplified MA microsatellite bands in IO. The size of the amplified bands and the sequence of the 5S rDNA in CK, MA and IO were also analyzed. It was found that the amplified 5S rDNA gene fragments in IO contained two fragments that were both the same size as those of CK and matched more than 90% with those of CK. Finally, the sex of IO was verified using gonadal tissue sections. The result showed that IO was not an all-female population; males were also present (36.7%). In summary, a series of validation methods confirmed that the induced offspring were gynogenetic fish, which is the basis for the subsequent genetic improvement of pure lines of high-quality koi. Full article

Background: Defective DNA repair systems result in the accumulation of mutations, loss of genomic integrity, and eventually cancer. Following initial malignant transformation due to specific DNA damage and defective DNA repair, cancer cells become reliant upon other DNA repair pathways for their survival. The co-occurrence of specific repair deficiencies brings catastrophic outcomes such as cell death for cancer cells and thus holds promise as a potential therapeutic strategy. Exploring the co-occurrence and mutual exclusivity of mutational signatures provides valuable knowledge regarding combinations of defective repair pathways that are cooperative and confer selective advantage to cancer cells and those that are detrimental and cannot be tolerated by them. Methods: Taking advantage of mutational signature profiling, we analyzed whole-genome sequences of 1014 breast cancers to reveal the underlying mutational processes and their interrelationships. Results: We found an inverse relationship between deficiencies of homologous recombination (HRd) and non-homologous end joining (NHEJd) with reactive oxygen species (ROS). Moreover, HRd and NHEJd co-occurred with APOBEC but were mutually exclusive with mismatch repair deficiency (MMRd) and ROS. Our analysis revealed that SBS8 and SBS39 signatures of currently unknown etiology correlate with NHEJd. ID1 and ID2 signatures co-occur with ROS and have mutual exclusivity with HRd, SBS8, SBS39 and NHEJd. The ID4 signature, with currently unknown etiology, has mutual exclusivity with HRd and NHEJd and co-occurred with ROS. On the other hand, the ID15 signature, with currently unknown etiology, co-occurred with SBS8, SBS39, HRd, NHEJd and DBS2, while having an inverse relationship with MMRd and ROS. Comparing the mutational signatures of HRd and non-HRd TNBC genomes reveals the unique presence of ROS signatures in non-HRd tumors and the lack of ROS signature in HRd tumors. Conclusion: Taken together, these analyses indicate the possible application of mutation signatures and their interactions in advancing patient stratification and suggest appropriate therapies targeting the make-up of individual tumors’ mutational processes. Ultimately, this information provides the opportunity to discover promising synthetic lethal candidates targeting DNA repair systems. Full article

Snakes are cytogenetically dynamic, characterized by largely conserved diploid chromosome numbers although displaying varied variable evolutionary stages of their sex chromosomes. This study examined four snakes, with a special focus on the genus Ptyas, to provide evolutionary insights into the evolution of ZW sex chromosomes. We performed an extensive karyotype characterization using conventional and molecular cytogenetic approaches, described for the first time the karyotype of Ptyas korros, and revisited the karyotype descriptions of P. mucosa, Chrysopelea ornata, and Fowlea flavipunctatus. We found that all species except F. flavipunctatus have highly heterochromatic W chromosomes enriched in satDNAs or microsatellite repeats. Repetitive sequences accumulate with the heterochromatinization of the W chromosome but are not necessarily associated with this process, demonstrating the dynamic makeup of snake sex chromosomes. Autosomal locus-specific and sex chromosome probes from Pogona vitticeps and Varanus acanthurus did not show hybridization signals in Ptyas snakes, suggesting divergent evolutionary pathways. This finding highlighted the dynamic nature of sex chromosome evolution in snakes, which occurred independently in lizards. Full article

The tumor suppressor protein p53 prevents the malignant transformation of cells by responding to DNA damage, oncogene activation, and abnormal growth signals including ribosome assembly defects. Under normal conditions, p53 activity is controlled by the regulatory proteins MDM2 and MDM4, which suppress its function through ubiquitin-mediated degradation and transcriptional inhibition. A subset of ribosomal proteins initiates the p53 response to impaired ribosome biogenesis. The ability of some ribosomal proteins to control MDM2 and MDM4 activities, and thereby p53, underscores an intriguing aspect of cell biology: proteins primarily known for their roles in ribosome function can exert extra-ribosomal functions. One notable example is the cellular RNA-protein complex involving RPL5, RPL11, and 5S rRNA (5S RNP) which inhibits MDM2 and stabilizes p53. Another RP, RPL22, is frequently mutated in cancers with microsatellite instability and its paralog RPL22L1 is often amplified. Recent studies have revealed that RPL22 directly modulates the alternative splicing of MDM4 to promote p53 activation, suggesting that the ribosomal protein-p53 relationship is more complex than previously thought. Cellular responses to ribosome biogenesis inhibition extend beyond general alterations in transcription and translation to actively determine cancer cell fate by selectively engaging tumor-suppressor pathways. RPL22’s effect on MDM4 and other mRNA splicing events is a striking example. A better understanding of the mechanisms involved could guide the development of improved cancer treatments. Full article