Discovery of the Novel HLA-DQB1*05:386 Allele in a Brazilian Volunteer Donor.
HLA-DQB1*05:386 differs from HLA-DQB1*05:01:01:01 by a non-synonymous substitution in exon 4.
Humans↗
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Positive selection and relaxed purifying selection contribute to rapid evolution of sex-biased genes in green seaweed Ulva.
BACKGROUND: The evolution of differences in gamete size and number between sexes is a cornerstone of sexual selection theories. The green macroalga Ulva, with incipient anisogamy and parthenogenetic gametes, provides a unique system to investigate theoretical predictions regarding the evolutionary pressures that drive the transition from isogamy to anisogamy, particularly in relation to gamete size differentiation and sexual selection. Its minimal gamete dimorphism and facultative parthenogenesis enable a rare window into early evolutionary steps toward anisogamy. RESULTS: By analyzing the expression profiles of sex-biased genes (SBGs) during gametogenesis, we found that SBGs evolve faster than unbiased genes, driven by higher rates of non-synonymous substitution (dN), indicating that SBGs are under stronger selective pressures. Mating type minus-biased genes (mt-BGs) exhibit higher dN/dS values than mating type plus-biased genes (mt+BGs), suggesting stronger selective pressures on mt-BGs, although this difference was not statistically significant (P = 0.08). Using branch-site and RELAX models, we found positive selection and relaxed purifying selection acting on a significant proportion of SBGs, particularly those associated with flagella function. CONCLUSIONS: This study highlights the selective pressures shaping anisogamy and provides insights into the molecular mechanisms underlying its evolution. The faster evolution of SBGs, particularly mt-BGs, and the positive selection on genes associated with motility, such as those related to flagella function, suggest the importance of enhanced gamete motility in the transition to anisogamy. These findings contribute to our understanding of sexual selection and the evolutionary forces that drive the differentiation of gamete size and number between sexes.
Selection, Genetic↗
Mitogenome assembly and phylogenetic relationships of Phalaris arundinacea.
INTRODUCTION: As a perennial herb of Poaceae, Phalaris arundinacea plays key roles in grazing, production, and soil and water conservation because of its well-developed rhizomes and seed dispersal. We assembled and annotated the first mitogenome of P. arundinacea to support evolutionary and taxonomic research. METHODS: We assembled and annotated the first complete mitochondrial genome of P. arundinacea by integrating Illumina short reads with Nanopore long reads via a hybrid assembly strategy. The genome architecture was comprehensively characterized, encompassing codon usage bias, repetitive sequence organization, and inter-organellar genetic exchange with the chloroplast genome. RESULTS AND DISCUSSION: Assembly of the P. arundinacea mitogenome revealed two circular structures with a combined length of 526,717 bp. The genome comprised a set of 37 protein-coding genes (PCGs), 27 tRNAs, and 8 rRNAs, with the rRNA genes exhibiting full assembly (100% coverage). The mitochondrial genome contained 154 forward and 164 palindromic repeats, along with 25 tandem repeats and 124 simple sequence repeats (SSRs). Notably, 102 SSRs were distributed on contig1, predominantly in tetrameric form. Furthermore, 376 RNA editing sites were predicted. A total of 104 fragments were integrated into the mitochondrial genome from the chloroplast, amounting to 55,866 bp of transferred sequence. Finally, phylogenetic analysis of 28 plant mitogenomes placed P. arundinacea closest to species within the genus Poa (P. chaixii and P. pratensis). Comparative analysis of non-synonymous-to-synonymous substitution rate (Ka/Ks) ratios across divergent species revealed that the mitochondrial genome of P. arundinacea underwent stabilizing evolutionary dynamics, characterized by predominant purifying selection with several lineage-specific variations in selective pressure. Our findings support the close phylogenetic relationship between P. arundinacea and species of the genus Poa and provide a reference mitochondrial genome resource for future comparative studies within Phalaris that incorporate broader taxon sampling. These results support deeper phylogenetic investigations of P. arundinacea and facilitate future work on its germplasm characterization and applied use.
Phalaris arundinacea↗
The Complete Chloroplast Genome and the Phylogenetic Analysis of Panicum bisulcatum (Thumb.) (Poaceae).
The chloroplast (cp) genome of Panicum bisulcatum (Thumb.), a significant agricultural weed, was sequenced and characterized to elucidate its genomic architecture, evolutionary dynamics, and phylogenetic relationships. The complete cp genome was assembled as a circular DNA molecule of 138,489 bp, exhibiting a typical quadripartite structure comprising a large single-copy (LSC, 82,260 bp), a small single-copy (SSC, 12,569 bp), and a pair of inverted repeats (IR, 21,830 bp each) regions. It encodes 135 genes, including 89 protein-coding genes, 49 tRNAs, and 8 rRNAs. Functional annotation revealed that most genes are involved in photosynthesis and genetic system. A total of 51 simple sequence repeats (SSRs) and 62 long repeats (LRs) were identified, providing potential molecular markers. Comparative analysis of IR boundaries highlighted both conserved features and species-specific expansion/contraction events among Panicum species. Phylogenomic analysis robustly placed P. bisulcatum within the genus Panicum, showing a closest relationship with P. incomtum and confirming the monophyly of the genus. Furthermore, single nucleotide polymorphism (SNP) analysis with its closest relative, P. incomtum, revealed 4659 SNPs, with a dominance of synonymous substitutions, indicating the action of purifying selection. This study provides the first comprehensive cp genomic resource for P. bisulcatum, which will facilitate future studies in species identification, phylogenetic reconstruction, population genetics, and the development of sustainable management strategies for this weed.
Phylogeny↗
CRISPR/Cas9-Mediated Site-Directed Mutagenesis of Genes in Klebsiella pneumoniae.
Constructing target-gene mutants with a common genetic background is crucial for elucidating gene function in antimicrobial resistance (AMR) research. Taking advantage of the single-guide RNA (sgRNA) and protospacer adjacent motif (PAM) sequence (3'-NGG) specificity of the Cas9 protein in the CRISPR/Cas9 (Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) system and codon degeneracy, the authors design a repair template that incorporates the desired point mutation while excluding the PAM sequence disrupted by a synonymous substitution, thereby preventing re-cleavage by CRISPR/Cas9. This method employs two available plasmids, pCasKP-apr and pSGKP-spe, offering straightforward operation and high screening specificity. As a result, the approach enables efficient generation of genetically defined mutant strains of Klebsiella pneumoniae (K. pneumoniae) and is readily adaptable to routine laboratory settings. Furthermore, the protocol minimizes off-target editing, shortens experimental timelines, reduces screening workload, and provides a reliable platform for investigating resistance mechanisms, validating candidate genes, and supporting functional genomics studies in clinically relevant bacterial pathogens.
Klebsiella pneumoniae↗
Identification of the Novel HLA-DQB1*02:02:41 Allele by Next-Generation Sequencing.
HLA-DQB1*02:02:41 differs from HLA-DQB1*02:02:01:01 by one synonymous nucleotide substitution at Codon 39 in Exon 2.
Humans↗
Identification of the Novel Allele HLA-DPB1*1782:01 in a Deceased Donor by Third-Generation Sequencing.
HLA-DPB1*1782:01 differs from HLA-DPB1*04:02:01:01 by a non-synonymous nucleotide substitution at codon 87.
Humans↗
Discovery of the novel HLA-DPB1*1789:01 Allele, a DBP1*02:01 Variant by Next Generation Sequencing.
HLA-DPB1*1789:01 differs from HLA-DPB1*02:01:02:89 by a non-synonymous nucleotide substitution in exon 4.
Humans↗
Discovery of the HLA-DPB1*1491:01 Allele, an HLA-DPB1*05:01:01:01, Variant by Next Generation Sequencing.
HLA-DPB1*1491:01 differs from HLA-DPB1*05:01:01:01 by a non-synonymous nucleotide substitution in Exon 2.
Humans↗
Identification of the Novel Allele, HLA-DQB1*05:368.
HLA-DQB1*05:368 differs from DQB1*05:01:01:02 by one non-synonymous nucleotide substitution in exon 2 at codon 29 (Arginine to Lysine).
Humans↗
The HLA-C*12:04:04 Allele Identified by Next Generation Sequencing in an Individual From Tamil Nadu, India.
Novel HLA-C*12:04:04 differs from HLA-C*12:04:02:02 by a single synonymous nucleotide substitution in exon 5 (ATC>ATT).
Humans↗
Characterisation of the Novel HLA-DQB1 Allele, HLA-DQB1*03:533 by Next Generation Sequencing.
HLA-DQB1*03:533 differs from HLA-DQB1*03:02:01:01 by a non-synonymous nucleotide substitution in exon 3.
Humans↗
Characterisation of the Novel HLA-DPA1*02:164 Allele Identified by Next Generation Sequencing.
HLA-DPA1*02:164 differs from HLA-DPA1*02:02:02:01 by a non-synonymous nucleotide substitution in exon 3 and an intronic nucleotide substitution in intron 1.
Humans↗
The Novel HLA-DQB1*06:03:60 Allele Identified by Next-Generation Sequencing and Confirmed by Nanopore Sequencing.
HLA-DQB1*06:03:60 differs from HLA-DQB1*06:03:01:01 by a single synonymous nucleotide substitution at position 174 in Exon 2.
Humans↗
Selection profiles in RNA viruses reflect the characteristics of viruses more than individual proteins.
Proteins that are exposed on the surface of a virus are frequently subject to strong selection to escape from neutralizing antibodies. To investigate whether surface-exposed (SE) and non-exposed (NE) proteins encoded by RNA viruses exhibit different patterns of evolution under selection, we analyzed 244 protein-coding genes from 28 species of RNA viruses representing 15 taxonomic families. First, we show that gene-wide rates of non-synonymous (dN) and synonymous (dS) substitutions do not differentiate between SE and NE proteins. To incorporate variation in substitution rates among codon sites, we inferred the posterior distribution over a fixed grid of dN and dS rates for each alignment. This 'evolutionary fingerprint' provides a common framework for comparing the selection profiles of non-homologous genes. Next, we computed the Wasserstein distance for every pair of fingerprints, which is analogous to amount of work required to reshape one distribution to another. After compensating for differences in genetic variation among alignments, we found a small but significant difference between the fingerprints of SE and NE proteins (PERMANOVA, P = 0.03). However, we observed larger and more significant effects of whether the virus is enveloped (P < 10-5) and the interaction between these factors (P=6.9×10-4). The latter effects were driven by high levels of purifying selection in capsid proteins of Picornaviruses. Furthermore, greater amounts of variation in fingerprints were explained by significant differences among virus families and modes of transmission (P < 10-5). These results imply the pattern of selection on a virus protein is shaped more by characteristics of the virus than the protein itself.
RNA Viruses↗
Identifying critical lysines in mammalian histone H3 with high-throughput CRISPR prime editing.
Histone post-translational modifications are fundamental to genome regulation, yet dissecting the functions of individual histone marks in mammals remains challenging due to the presence of multiple histone gene copies. Here we develop a high-throughput clustered regularly interspaced short palindromic repeats (CRISPR) prime editing platform enabling precise, reversible and combinatorial mutagenesis of canonical and noncanonical histone H3 genes within their native genomic context. Using systematic lysine-to-arginine substitutions benchmarked against synonymous controls, we identify key residues, including H3K4, H3K9, H3K14, H3K18 and H3K79, whose mutation compromises fitness in mouse embryonic stem cells. We further show that H3K56, linked to genome stability in yeast and Drosophila, has a conserved role in mammalian cells. Through analysis of selected double mutants, we uncover functional crosstalk across residues, with combinations such as H3K27R + H3K36R impairing stem cell self-renewal and altering transcription. Altogether, this study establishes a functional map of histone H3 lysines in mammals and provides a broadly applicable platform for systematic dissection of chromatin regulation.
Histones↗
The Novel HLA-E*01:152 Allele Identified in African Populations Using Next-Generation Sequencing.
E*01:152 differs from E*01:03:05:01 by a non-synonymous A>G substitution at gDNA position 958 (exon 3).
Humans↗
In silico prediction of the impact of genomic variations in the small conductance calcium activated potassium channel SK3 structure and function.
The small-conductance calcium-activated potassium channel SK3, encoded by the KCNN3 gene, plays a critical role in regulating dopaminergic neuron (DN) firing patterns by modulating after hyperpolarization currents. SK3 dysfunction has been implicated in neuropsychiatric and neurodegenerative disorders. We analyzed structural and functional consequences of KCNN3 splicing and genetic variation. Alternative splicing variants of the KCNN3 gene were retrieved from the Ensembl database and aligned using T-Coffee, manually inspected and curated. Protein domains were identified with Pfam 35.0, SMART 9.0, and InterPro 98.0, and visualized. An AlphaFold2 model of SK3 full-length protein (UniProt: Q9UGI6) used as reference and structural models of its splicing variants were predicted with ColabFold. Functional domains (S1-S6 transmembrane helices, H5 pore loop, and calmodulin-binding) were defined and superimposed onto the AlphaFold2 reference. Domain integrity was assessed based on completeness of all expected residue indices within each functional region. SNPs and CNVs across all coding KCNN3 splicing variants were analyzed, classified, and filtered to isolate pathogenic variants prioritizing non-synonymous amino acid substitutions. Differential variant impacts across splicing isoforms were assessed by mapping variant positions to individual transcript protein sequences and used to predict functional consequences. Two long and two short splicing variants are known. Short variants lack the motif required for potassium channels. Pathogenic variants result from missense mutations resulting in amino acid substitutions. In all cases, the consequential effects depend on the specific location and role of the amino acid being changed.
SK3 channels↗