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PubMed2026

Transcriptomic changes in the gut mucosa of fasting northern elephant seal pups reveal immune modulation during early microbiome establishment.

Fasting is an integral component of the life-history of many species. Following abrupt weaning, northern elephant seal pups (Mirounga angustirostris) undergo an extended post-weaning fast of approximately 60 days. During this period, enteric bacterial diversity increases, suggesting that host immune regulation may facilitate the establishment of microbial communities. However, the molecular processes occurring within the intestinal mucosa during this transition remain poorly understood. To investigate these mechanisms, we characterized transcriptional changes in the enteric mucosa of male and female northern elephant seal pups sampled at weaning and after one month of fasting. Total RNA isolated from rectal swabs was sequenced and aligned to the Mirounga angustirostris reference genome. Differential gene expression and gene set enrichment analyses were used to identify genes and pathways associated with fasting and sex-specific responses. Fasting was accompanied primarily by transcriptional downregulation, including genes involved in antimicrobial defense, inflammation, protein turnover, and epithelial remodeling. In contrast, several genes associated with B-cell activity and immune recognition were upregulated. Gene Set Enrichment Analysis revealed coordinated activation of immune-regulatory pathways indicating dynamic modulation of intestinal immunity rather than generalized immune suppression. Pronounced sex-specific differences were also observed. Male pups exhibited transcriptional patterns consistent with enhanced immune tolerance, whereas females showed broader immune-pathway activation, including enrichment of pro-inflammatory and stress-response pathways. Several non-coding RNAs also displayed sex-specific changes in expression. Together, these findings suggest that fasting induces transcriptional remodeling of the gut and may contribute to immune regulation during a critical period of microbiome establishment in northern elephant seal pups.

Animals↗
PubMed2025

Mapping the oral microbiome opens links to periodontitis.

Many microbiome analysis techniques can only detect the microbes present in the reference genome database used. In this issue of Cell Host & Microbe, Cha et al. establish an improved genome database of the human oral microbiome, which they use to discover a connection between periodontitis and an enigmatic bacterial phylum.

Humans↗
PubMed2026

Meta-PseU: A meta-classifier for robust prediction of RNA pseudouridine modification sites from long sequences.

BACKGROUND AND OBJECTIVES: Pseudouridine (Ψ) represents one of the most abundant and conserved RNA modifications. Ψ provides an additional hydrogen-bond donor that enhances RNA structural stability and modulates translation. It participates in diverse biological processes, including RNA-protein interactions, splicing, translational control, and stress responses. Aberrant pseudouridylation is implicated in cancer, neurodegenerative disorders, and autoimmune diseases. Despite its biological importance, experimental identification of Ψ sites remains time-consuming and costly, limiting the feasibility of transcriptome-wide profiling. Computational approaches have therefore become essential complements to experimental techniques. However, state-of-the-art machine-learning and deep-learning predictors often suffer from limited generalizability due to small training datasets. To overcome these issues, we aim at constructing new long-sequence datasets and developing a novel Ψ site predictor. METHODS: New long-sequence datasets were constructed as benchmarks for RNA Ψ-site prediction. The Ψ modification sites in RMBase 3.0 were mapped to the reference genomes across three species of human, mouse, and yeast, and the RNA sequences with a length of 201 were generated by extending the upstream and downstream from the mapped, central sites. To eliminate sequence redundancy, the sequences were clustered using CD-HIT with a 70% sequence identity threshold. We developed Meta-PseU, a logistic regression-based meta-classifier that considered 118 machine learning and deep learning classifiers. The datasets and programs are freely accessible at https://github.com/kuratahiroyuki/MetaPseU. RESULTS: By optimizing model configuration, we proposed the Meta-PseU model stacking 32 machine learning and deep learning classifiers out of 118 classifiers. Meta-PseU substantially improved model generalizability, overcoming a key limitation of existing approaches. It greatly outperformed state-of-the-art predictors and achieved increasing accuracy with increasing sequence length. CONCLUSIONS: Long-sequence datasets were newly constructed as benchmarks for RNA Ψ-site prediction. Meta-PseU offers a new framework for robust Ψ-site identification by using long sequences.

Pseudouridine↗
PubMed2026

TNF-NF-κB signaling mediates immune-biomineralization crosstalk during shell repair under ocean acidification in Mytilus edulis.

Ocean acidification (OA) impairs biomineralization in bivalves, but its effects on immune-biomineralization crosstalk during shell repair remain unknown. Here, we exposed adult Mytilus edulis bearing standardized shell perforations to three pH levels (8.1, 7.9, and 7.7) for up to 40 days. OA slowed early repair and caused microstructural disorganization and an approximately 87% reduction of compressive strength at pH 7.7, yet the damaged area appeared largely closed by day 15, suggesting a decoupling between morphological closure and functional recovery. In addition, transcriptomic profiling of hemocytes and mantle tissue, based on an average of 6.5 Gb of clean reads per sample mapped to the M. edulis reference genome (NCBI Assembly GCF_000511035.1), revealed that these shell-level defects were accompanied by coordinated immune and metabolic reprogramming. Hemocytes, the primary immune effector cells of bivalves, exhibited pH- and time-dependent shifts with moderate acidification (pH 7.9) promoting inflammatory transcripts, whereas severe acidification (pH 7.7) suppressed these signals while upregulating stress-associated pathways; both treatments consistently downregulated lysosomal proteases and NF-κB negative regulators. The mantle, a primarily mineralizing organ, paradoxically upregulated immune-related genes while suppressing oxidative phosphorylation and extracellular matrix pathways. This tissue-level imbalance, with hemocytes recruited but functionally constrained and mantle metabolically suppressed yet immunologically activated, points to TNF-NF-κB pathway modulation as a key mediator of shell repair under acidification. Our findings demonstrate that visible shell closure masks underlying structural and mechanical failure, and that immune regulation, rather than simple suppression or activation, critically shapes the repair outcome. These results advocate for multifunctional indicators beyond closure area to assess shell integrity in acidified marine environments.

Animals↗
PubMed2026

Diverse structures of mcr-10-bearing plasmids and high colistin resistance in Enterobacter cloacae complex clinical isolates from South Korea.

BACKGROUND: The emergence of mcr-mediated colistin resistance in Enterobacter cloacae complex (ECC) poses a significant threat to antimicrobial therapy. Among mcr variants, mcr-10 has been identified in various environments, but its genetic diversity, structural context, and functional role in colistin resistance remain unclear. METHODS: We investigated 183 ECC isolates and identified 60 colistin-resistant strains through minimum inhibitory concentration (MIC) testing. The presence of mcr-10 was screened using reference genomes from NCBI, and whole plasmid sequencing was conducted on mcr-10-positive isolates. The genetic environment of mcr-10 was analyzed via synteny and structural annotation. RESULTS: Whole-plasmid sequencing of eight mcr-10-positive ECC isolates identified three replicon types among the mcr-10-harboring plasmids: IncFIB (n=3), IncFII (n=3), and IncFII/IncFIB (n=2). Although all plasmids shared the xerC-mcr-10 cassette, they lacked a conserved backbone and showed diverse genetic contexts with variable insertion sequences near mcr-10, indicating marked structural heterogeneity. No additional antimicrobial resistance genes were detected on these plasmids. When introduced into E. coli DH5α, the plasmids increased colistin MICs only modestly, whereas representative plasmids transferred into colistin-susceptible E. roggenkampii and E. kobei conferred high-level resistance comparable to that of the parental mcr-10-positive isolates. Consistently, qRT-PCR showed higher mcr-10 expression in ECC transformants than in E. coli under colistin exposure, supporting a hostdependent effect on mcr-10-mediated colistin resistance. CONCLUSION: These findings highlight the diversity of mcr-10-carrying plasmids and suggest that mcr-10-mediated colistin resistance is shaped by the host genetic background. Further studies are needed to clarify the mechanisms underlying mcr-10 expression.

Colistin↗
PubMed2026

Multiomic insights into fungal polylactic acid degradation: Metabolic adaptation and hydrolytic mechanisms of Sporobolomyces pararoseus.

Polylactic acid (PLA), a biodegradable polyester from renewable resources, is a sustainable alternative to petrochemical plastics. However, its environmental degradation is inefficient naturally, requiring specific microbial activities. While bacterial PLA-degrading mechanisms are well documented, fungal degrading systems-particularly their molecular mechanisms-are underexplored.We isolated Sporobolomyces pararoseus ZRQ01 from the gut microbiota of PLA-fed mealworms. This fungal strain noticeably degraded PLA in PLA-containing medium supplemented with 2% glucose. Biodegradation assays revealed 22.8% loss of the PLA film weight after 35 days of incubation, and scanning electron microscopy confirmed extensive surface erosion and pore formation. Integrated transcriptomic and proteomic analyses, together with the reference genome of S. pararoseus ZRQ01, revealed that S. pararoseus ZRQ01 upregulates hydrolytic enzymes at both transcript and protein levels to cleave PLA into lactic acid. After lactic acid is transferred into S. pararoseus ZRQ01 cells by monocarboxylate transporters with increased abundance, it is assimilated by pathways of pyruvate metabolism and the TCA cycle with increased protein abundance. Intriguingly, upregulation of genes in autophagy-related and MAPK signaling pathways underscores an adaptive stress response potentially supporting cellular homeostasis and degradation-related gene expression. Our results highlight S. pararoseus ZRQ01's metabolic potential for bioremediation and offer insights into fungal bioplastic degradation pathways.

Polyesters↗
PubMed2004

Development and application of a capsid VP1 (region D) based reverse transcription PCR assay for genotyping of genogroup I and II noroviruses.

Noroviruses (NoV), previously called "Norwalk-like viruses", have emerged as the single most important cause of acute gastroenteritis worldwide. Most diagnostic reverse transcription-polymerase chain reaction (RT-PCR) assays target the viral RNA-dependent RNA polymerase; however, the major capsid protein (VP1) is the reference genomic region for establishing genotypes. In this study, we analyzed complete NoV VP1 sequences (n=100) and determined a region (region D) that was most suitable to differentiate between genotypes. Within region D, we designed two genogroup specific, broadly reactive, degenerate primer sets (GI and GII). The region D primers were evaluated in a single-tube one-step RT-PCR assay using a panel of 81 (31 GI, 50 GII) NoV strains from both outbreaks and sporadic cases. In total, 95% of the samples tested positive using the new region D primer sets. Phylogenetic analysis of region D sequences (36 deduced amino acids for GI, 56 deduced amino acids for GII), revealed 19 clusters (7 within GI and 12 within GII) including three new genetically distinct clusters, two of which were unresolved using region A sequences. Phylogenetic analysis of the complete VP1 sequences revealed identical grouping of strains and confirmed the newly identified clusters using region D. In summary, we successfully developed and evaluated a broadly reactive RT-PCR assay for reliable genotyping of GI and GII noroviruses.

Base Sequence↗
PubMed2026

Molecular characterisation and mutational analysis of antimicrobial resistance genes in Helicobacter pylori isolates in Erbil, Iraq.

BACKGROUND: Antibiotic resistance in Helicobacter pylori poses a significant challenge to the effective eradication of infection worldwide. Understanding molecular mechanisms of resistance is essential for guiding treatment strategies. This study aimed to investigate the molecular basis of antimicrobial resistance in Helicobacter pylori isolates and their associated mutation frequencies. METHODS: In this cross-sectional study, gastric biopsy specimens were collected from 203 patients at Rizgary Hospital in Erbil, Kurdistan Region, Iraq, who underwent endoscopy for dyspepsia-related symptoms. Of the 137 positive patients, 91 Helicobacter pylori isolates were confirmed by colony morphology, Gram staining, and biochemical tests; 63 were successfully subcultured for antimicrobial susceptibility testing (culture success rate: 69.2%). Antimicrobial susceptibility testing was performed by the agar dilution method to determine the minimum inhibitory concentrations. The sequences of specific genes were examined and analysed by next-generation sequencing. Multiple sequence comparisons were performed to identify resistance-related genes and mutations, using 26695 (NC_000915.1) as the reference genome. RESULTS: Only two isolates (3.17%) were susceptible to all antibiotics examined. The frequency of metronidazole resistance was highest (85.71%), followed by levofloxacin (55.55%), clarithromycin (52.38%), amoxicillin (26.98%), tetracycline (6.35%), and rifabutin (4.76%). Mutations in the rdxA and frxA genes correlated with metronidazole resistance, while GyrA protein mutations at positions 87 and 91 were linked to levofloxacin resistance. Clarithromycin resistance was mainly associated with A2142G and A2143G mutations in 23S rRNA. Amoxicillin resistance (26.98%) was associated with mutations in the pbp1A gene, whereas resistance to tetracycline and rifabutin was infrequent. CONCLUSIONS: This study provides the first molecular surveillance data on antimicrobial resistance in Helicobacter pylori in northern Iraq, offering valuable regional evidence to guide local eradication strategies. The relatively high amoxicillin resistance, together with the elevated resistance to metronidazole, levofloxacin, and clarithromycin, underscores the need for susceptibility-guided therapy and continuous local antimicrobial resistance surveillance.

Antibiotic resistance↗
PubMed2003

The nicotinic acetylcholine receptor gene family of the pufferfish, Fugu rubripes.

Nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission at nerve-muscle junctions and in the brain. However, the complete gene family of nAChRs has not so far been reported for any vertebrate organism. We have identified the complete nAChR gene family from the reference genome of the pufferfish, Fugu rubripes. It consists of 16 alpha and 12 non-alpha candidate subunits, making it the largest vertebrate nAChR gene family known to date. The gene family includes an unusual set of muscle-like nAChR subunits comprising two alpha1s, two beta1s, one delta, one epsilon, and one gamma. One of the beta1 subunits possesses an aspartate residue and N-glycosylation sites hitherto shown to be necessary for delta-subunit function. Potential Fugu orthologs of neuronal nAChR subunits alpha2-4, alpha6, and beta2-4 have been identified. Interestingly, the Fugu alpha5 counterpart appears to be a non-alpha subunit. Fugu possesses an expanded set of alpha7-9-like subunits and no alpha10 ortholog has been found. Two new candidate beta subtypes, designated beta5 and beta6, may represent subunits yet to be found in the human genome. The Fugu nAChR gene structures are considerably more diverse than those of higher vertebrates, with evidence of "intron gain" in many cases. We show, using RT-PCR, that the Fugu nAChR subunits are expressed in a variety of tissues.

Amino Acid Sequence↗
PubMed2017

Circular RNA profiling reveals an abundant circLMO7 that regulates myoblasts differentiation and survival by sponging miR-378a-3p.

Circular RNAs (circRNAs) have been identified from various tissues and species, but their regulatory functions during developmental processes are not well understood. We examined circRNA expression profiles of two developmental stages of bovine skeletal muscle (embryonic and adult musculus longissimus) to provide first insights into their potential involvement in bovine myogenesis. We identified 12 981 circRNAs and annotated them to the Bos taurus reference genome, including 530 circular intronic RNAs (ciRNAs). One parental gene could generate multiple circRNA isoforms, with only one or two isoforms being expressed at higher expression levels. Also, several host genes produced different isoforms when comparing development stages. Most circRNA candidates contained two to seven exons, and genomic distances to back-splicing sites were usually less than 50 kb. The length of upstream or downstream flanking introns was usually less than 105 nt (mean≈11 000 nt). Several circRNAs differed in abundance between developmental stages, and real-time quantitative PCR (qPCR) analysis largely confirmed differential expression of the 17 circRNAs included in this analysis. The second part of our study characterized the role of circLMO7-one of the most down-regulated circRNAs when comparing adult to embryonic muscle tissue-in bovine muscle development. Overexpression of circLMO7 inhibited the differentiation of primary bovine myoblasts, and it appears to function as a competing endogenous RNA for miR-378a-3p, whose involvement in bovine muscle development has been characterized beforehand. Congruent with our interpretation, circLMO7 increased the number of myoblasts in the S-phase of the cell cycle and decreased the proportion of cells in the G0/G1 phase. Moreover, it promoted the proliferation of myoblasts and protected them from apoptosis. Our study provides novel insights into the regulatory mechanisms underlying skeletal muscle development and identifies a number of circRNAs whose regulatory potential will need to be explored in the future.

Animals↗
PubMed2026

Unveiling clinical and genetic landscapes of MMA and CBS: insights from whole exome sequencing in a tertiary care setting.

BACKGROUND: MMA and CBS deficiency are rare autosomal recessive metabolic disorders caused by defects in cobalamin metabolism and cystathionine-beta-synthase activity, respectively. Advanced molecular genetic techniques, have become essential for diagnosing these conditions. This study aimed to analyze the genetic variations in three MMA and four CBS deficiency cases using WES and correlate the findings with clinical, biochemical, and treatment outcomes. METHODS: Clinical evaluation, biochemical testing, neuroimaging, and WES were performed. WES data were analyzed using the reference genome GRCh37, and variants were classified according to ACMG guidelines. Treatment outcomes were monitored for three months post-intervention. RESULTS: In MMA cases, a homozygous pathogenic variant (c.394 C > T, p.Arg132Ter) in MMACHC was identified in all three patients. Biochemical abnormalities included methylmalonic aciduria, elevated homocysteine, and megaloblastic anemia. Hydroxycobalamin therapy improved behavioral, cognitive, and dermatological symptoms, though residual neuropathy persisted in one case. In CBS deficiency, pathogenic variants in CBS (c.992 C > T, p.Ala331Val; c.862 G > A, p.Ala288Thr; c.700 G > A, p.Asp234Asn) were identified. Clinical features included developmental delayed milestones, lens dislocation, and vascular complications. Treatment outcomes varied based on early diagnosis and compliance. CONCLUSION: This study highlights the importance of newborn screening program with WES in diagnosing and managing MMA and CBS deficiency, facilitating early intervention, improving clinical outcomes, and supporting precision medicine approaches. IMPACT: Early newborn screening and diagnosis are critical for effective treatment and improved patient outcomes. Novel clinical and pathogenic variants will expand the current understanding of these disorders. WES enhances the diagnostic precision for MMA and CBS deficiency, facilitating timely intervention and superior clinical management. Accurate and early detection of treatable IEMs through NBS can significantly reduce disease burden and healthcare costs.

Child, Preschool↗
PubMed2026

Appreciating diversity: a review of the Iranian genomic landscape.

Understanding population structure is crucial for designing and interpreting human genetic studies. This is of particular importance for Iran as a large, ethnically diverse country whose population has often been treated as a genetically homogenous entity. Here, we synthesize published literature on the genetic structure of the Iranian population. We further complement this by recapitulating the geographic, historic, and ethnic background, by comparisons with neighboring countries, and by reviewing autozygosity in Iran. This synthesis confirms large genetic diversity, likely building upon an autochthonous component that was reshaped by multiple migrations. The substantial autosomal substructure falls apart into groups of largely shared genetic ancestry (Central Iranian Cluster) and those with substantial admixture in the past. Structure with respect to uniparental markers is less pronounced. We also find consistency for generally high but varying levels of autozygosity, influenced by ethnicity, residence, and socioeconomic factors. Finally, we recapitulate some examples for geographical differences in disease prevalence and (founder) mutation carrier frequency. Our synthesis emphasizes the need to account for this diversity in human genetic studies in the Iranian population. We provide conclusions for the design of such studies and state expectations on the transferability of genetic findings and genomic predictions, such as polygenic scores, within Iran as well as to neighboring countries. Iran's diversity and geographic location provide renewed motivation for conducting population genetic and ancient DNA studies as well as providing genomic reference resources in this part of the world.

Journal Article↗
PubMed2026

Biosynthesis and heterologous production of the α-agarofuran scaffold of Celangulin V from Celastrus angulatus.

Celangulin V is a widely used biopesticide derived from Celastrus angulatus, and features antifeedant and insecticidal properties as a dihydro-β-agarofuran (DHβAF) sesquiterpenoid. Its biosynthesis remains largely unexplored. Here, we assemble a chromosome-level and haplotype-resolved reference genome of C. angulatus, with each haplotype assembled into 23 pseudochromosomes and achieving scaffold N50 of 14.31 and 14.01 Mb, respectively. This high-quality genome reveals that a recent β whole-genome triplication (β-WGT) event occurred ~34.3 million years ago, and that the expansion of sesquiterpene synthases and cytochrome P450s from the CYP71BE family results from whole-genome duplication (WGD) event and tandem duplication, respectively. We identify CaTPS16 as a γ-eudesmol synthase, and show that CYP71BE416 further catalyzes the γ-eudesmol to tetrahydrofuran ring α-agarofuran for Celangulin V biosynthesis. We further achieve the de novo synthesis of α-agarofuran in Saccharomyces cerevisiae through combined coexpression of these genes. This study has significantly increases the available genomic resources of the Celastraceae family, improves our understanding of the biosynthetic origins and evolution of the tetrahydrofuran ring in DHβAF sesquiterpenoids, and enables its heterologous bioproduction in microbial chassis.

Celastrus↗
PubMed2026

Modeling reptile virus infection in vitro using Python regius airway organoids.

Zoonoses pose substantial global health risks, highlighting the need to better understand animal-to-human transmission. Reptiles are increasingly recognized as hosts of diverse pathogens, including numerous viruses, yet the diversity and prevalence of reptile pathogens, as well as their potential risk to humans, remain poorly understood. Here, we establish and characterize airway organoids derived from Python regius, providing an in vitro model to study reptile airway infection. Through de novo assembly of a Python regius reference genome, we characterize airway organoids at single-cell resolution, which suggests the presence of diverse cell populations including ionocytes, ciliated, secretory, goblet, endocrine, tuft, and basal cells. The organoids support productive infection with Ball Python Nidovirus (BPNV) and mount a robust epithelial antiviral response through the induction of interferon-stimulated genes, cytokines, and genes involved in chemical defense. As a proof-of-concept, treating organoids with antiviral drugs during infection reduces BPNV levels, highlighting the model's utility for drug testing. By providing a reductionist system of the serpentes airway, these organoids constitute a physiologically relevant in vitro model to study reptile viruses and host-pathogen interactions in their native host.

Animals↗
PubMed2026

Population history rather than tree age contributes to the evolutionary importance of ancient trees in an endangered conifer.

Ancient trees are in global decline and face increasing conservation challenges. Their exceptional longevity has fostered the view that they are genetic reservoirs, yet whether old age is synonymous with unique genetic variation remains unclear. Here we assembled a ~8-Gb chromosome-level reference genome for the critically endangered conifer Glyptostrobus pensilis, now largely restricted to southern China with scattered populations in Vietnam and Laos, and resequenced 147 individuals, including 64 ancient (>100 years old and persisting in human-dominated landscapes), 33 wild and 50 recently cultivated individuals. Ancient individuals comprised both likely natural relics and historically introduced individuals and formed two deeply divergent lineages and one ancestral-admixed group, each with distinct demographic histories of prolonged contraction and genomic erosion. Lineage identity explained more variation in genome-wide diversity, inbreeding and genetic load than the three conservation types, despite broad differences in age structure. Rare-allele analyses revealed pronounced heterogeneity among ancient trees: only relic and ancestral-origin individuals from high-diversity lineages contributed substantial unique variation, much of which is poorly represented in wild and cultivated populations. Together, our findings suggest that ancient trees are not uniformly genetically irreplaceable and that, at least in this conifer, evolutionary importance is shaped more strongly by population history than by age alone.

Endangered Species↗
PubMed2026

How the social lives of bacteria affect their pangenome.

Although the study of microbes started with type strains and reference genomes, advances in sequencing technology and new interest in mixed microbial communities have made us aware that a single genome cannot and does not reflect the diversity of a given bacterial species. Bacteria rarely occupy an environmental or host niche alone and quickly diversify into strains upon colonization of a new niche. The genetic diversity present within a phylogenetically related set of bacterial strains (the 'pangenome') is influenced by the niche that they occupy and how they interact with the other microorganisms that they share that niche with. In this review, I examine how the social lives of bacteria can affect their genetic diversity and the bioinformatic techniques that we use to detect that diversity.

Bacteria↗
PubMed1998

Hepatitis C virus infection: virus/host interactions.

Infection with the hepatitis C virus (HCV) is a leading cause of chronic liver disease world-wide. This paper examines our current understanding of the complex relationship between HCV and its host, especially potential mechanisms of viral persistence and resistance to interferon therapy, and the pathogenesis of liver injury in chronic HCV infection. HCV infection leads to viral persistence and chronic disease in a very high proportion of cases, despite broad humoral and cellular immunological responses to viral proteins. These responses may be thwarted by the high rate of mutation, which leads to the generation of a highly variable mixture of closely related genomes, referred to as a quasispecies, that persists and continuously evolves in infected individuals. Understanding this, and other mechanisms of viral persistence and immune escape, will be essential in developing effective future therapeutic and preventive strategies. As far as the pathogenesis of chronic hepatitis C is concerned, two non-mutually exclusive hypotheses have been raised: first, that HCV can be cytopathic and induce liver lesions by replicating in infected hepatocytes, and second, that liver lesions could be the result of specific or non-specific immune responses. In the absence of a cell-culture model, the direct cytopathogenicity of the virus cannot be assessed confidently. Recent data suggest that cytotoxic T cells and cytokines produced by both CD4+ (T helper) and cytotoxic T cells may be responsible for much of the damage that occurs in the livers of infected patients.

Amino Acid Sequence↗
PubMed2026

The archaeal roots of eukaryotic life.

Resolving the biological and geological events that led to the origin of eukaryotes is an ongoing challenge in biology. A major step in the evolution of complex cellular life was the merger between an ancestral host cell and a bacterium (that became the mitochondrion) some two billion years ago. Recently, metagenomics has enabled the reconstruction of a broad diversity of genomes, referred to as the Asgard Archaea. The Asgards are monophyletic with eukaryotes on the tree of life. Asgards have an array of genes, previously thought exclusive to eukaryotes, involved in cellular trafficking, the ubiquitin system, endosomal sorting, and cytoskeleton formation, with growing evidence demonstrating the functions of these proteins mirror those in eukaryotes. This gene repertoire suggests that these Archaea are descendants of the archaeal host from which eukaryotes evolved. Increased sampling has revealed that Asgard lineages are metabolically versatile and play key roles in various ecosystems and uncovered evolutionary transitions between Archaea and eukaryotes, such as innovations in eukaryotic defense systems. The positioning of eukaryotes in the Asgards is debated, but eukaryotes appear to branch within the Heimdallarchaeia. Lineages within this group, particularly Hodarchaeales and Kariarchaeaceae, contain a broad repertoire of eukaryote-like traits, including high-energy yielding metabolisms. Observing and studying Asgard interactions with bacterial descendants of mitochondria in a modern setting will transform our understanding of the origin of complex cellular life.

Archaea↗