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PubMed2026

The cold case of state transition 7 (stt7) mutants of Chlamydomonas reinhardtii, solved by whole-genome sequencing.

The process of State Transitions (ST) corresponds to an STT7 kinase-driven redistribution of the transmembrane LHCII antenna proteins between Photosystem II (PSII) and Photosystem I (PSI), which results from changes in their phosphorylation state. For the past two decades, two LHCII-kinase mutants, stt7-1 and stt7-9, have been instrumental in the study of STs in Chlamydomonas reinhardtii, the former being a null mutant for the kinase but quasi-sterile in crosses, while the latter, although fertile, has a leaky phenotype. Using long-read sequencing, this study further characterized the genetic lesions of the stt7 mutant strains through whole-genome reconstruction and de novo chromosome assembly. In addition, two new stt7 null mutants were generated, one derived by crosses from the original stt7-1 and one obtained by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-associated protein 9 (Cas9) technology. This work provides a comprehensive genomic characterization of the original stt7-1 null mutant, revealing extensive chromosomal rearrangements and high levels of aneuploidy, associated with increased cell size and meiotic dysfunction. Reassessment of their physiology and genetic backgrounds highlights the need for caution in interpreting genetic information. We thus produced more reliable null mutants for the LHCII-kinase, amenable to genetic crosses for the study of STs in a variety of genetic backgrounds.

Chlamydomonas reinhardtii↗

PubMed2026

Epigenetics and In Silico Transcriptome Analysis of Pediatric Acute Myeloid Leukemia.

Pediatric acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy that accounts for about 15%-20% of childhood leukemias. Despite therapeutic advances, relapses remain common, and survival for high-risk patients is below 60%. Unlike adult AML, pediatric AML displays distinct genetic mutations, including FLT3-ITD, NPM1, KMT2A rearrangements, and core-binding factors (CBF) fusions, as well as extensive epigenetic dysregulation. Aberrant DNA methylation, histone modifications, and altered non-coding RNA expressions disrupt hematopoietic differentiation and activate oncogenic transcriptional networks. Recent advances in silico transcriptomic analysis have transformed the study of pediatric AML by integrating gene expression and epigenetic data to identify molecular drivers and regulatory networks. Computational RNA-seq pipelines and pathway analyses have highlighted key epigenetic regulators, including DNMT3A, TET2, and HDACs, as potential therapeutic targets. Multi-omics approaches combining transcriptomic, methylomic, and chromatin accessibility data are increasingly used to define biomarkers for diagnosis, prognosis, and therapeutic response. This review provides a comprehensive overview of the molecular and epigenetic landscape of pediatric AML, emphasizing the power of in silico transcriptome analysis to uncover disease mechanisms, refine patient stratification, and guide the development of precision-based epigenetic therapies aimed at improving long-term outcomes in children with AML.

Humans↗

PubMed2026

A Meta-analysis of the intervention effects of ball sports on children with autism Spectrum disorder.

PURPOSE: To evaluate the overall efficacy of ball sports interventions for children with autism spectrum disorder (ASD) and to explore potential moderators that may influence intervention outcomes. METHODS: Randomized controlled trials were retrieved from nine databases (e.g., CNKI, PubMed) from 2000 to April 2025. Meta-analysis was conducted using RevMan 5.4 and Stata 18.0, with subgroup analyses by age, duration, frequency, session length, and ball sport type. RESULTS: A total of 14 randomized controlled trials involving 406 children were ultimately included. Meta-analysis results indicated that ball sports had a significant overall intervention effect on children with ASD (SMD = -1.12, 95% CI: -1.56, -0.68, P < 0.05), with significant improvements observed in social skills (SMD = -0.55), verbal communication (SMD = -0.85), and behavioral problems (SMD = -1.10). Subgroup analysis indicated that interventions involving mini-basketball or other ball sports with simple rules-conducted over a 12-week period, 3-5 times per week, for 30-60 min per session-yielded better outcomes, with children aged 3-6 years showing more consistent benefits. CONCLUSION: Ball-based interventions effectively alleviate core ASD symptoms. Structured moderate-intensity programs are recommended as adjunct therapies. Future studies should standardize protocols and examine long-term benefits.

Humans↗

PubMed2026

Electrospun Nanofiber Dressings for Diabetic Wounds: From Single-Layer to Intelligent Composite Systems.

Diabetic chronic wounds have become a major challenge for clinical treatment due to their complex pathological microenvironment, including persistent inflammatory response, angiogenesis disorder, excessive oxidative stress, and susceptible infection. Traditional dressings as a passive barrier have difficulty meeting the above multiple treatment needs. Electrospinning technology, with its ability to mimic the fibrous network structure of the natural extracellular matrix (ECM), offers a high specific surface area, controllable porosity, and excellent drug-loading capacity, making it an ideal platform for developing a new generation of multifunctional wound dressings. This article provides a systematic review of the research progress on electrospun nanofiber dressings in the treatment of diabetic wounds, focusing on the design evolution from basic single-layer structures to advanced complex structures and elucidating the mechanisms of action and quantifiable effects of each structural type in addressing specific pathological challenges. We also compared the current status of clinical translation for electrospun dressings with that of other advanced wound care platforms and proposed a standardized preclinical evaluation framework. A large number of research data show that these advanced designs can effectively improve the quality of healing. Finally, this paper points out the challenges faced by this field, such as scalable fabrication, in vivo reliability of smart systems, and long-term biosafety, and provides theoretical basis and technical reference for the design of efficient and intelligent electrostatic spinning diabetic wound dressings.

Nanofibers↗

PubMed2026

The circadian clock proteins PRR modulate root hair development via the RHD6/RSL module in Arabidopsis.

Root hairs, derived from trichoblasts, are critical for plant growth and environmental adaptation. Although environmental cues are known to influence root hair development, how endogenous timing systems such as the circadian clock integrate into the core transcriptional network governing root hair formation remains unclear. Here, we show that the circadian clock-associated protein PSEUDO-RESPONSE REGULATOR5 (PRR5) physically interacts with ROOT HAIR DEFECTIVE6 (RHD6) and RHD6 LIKE1 (RSL1), two basic helix-loop-helix transcription factors essential for root hair initiation. Genetic analyses suggest that PRR proteins contribute to root hair development under long-day conditions in Arabidopsis thaliana. Simultaneous disruption of PRR5, PRR7, and PRR9 results in defective root hairs, whereas PRR5 overexpression markedly increases root hair density and length. Transcriptomic and RT-qPCR analyses reveal that PRRs enhance the expression of RHD6, RSL1, and multiple downstream root hair-responsive genes, while modulating their temporal expression patterns. Furthermore, PRR5-mediated root hair promotion requires RHD6/RSL1, and PRR proteins enhance RHD6-dependent activation of the RSL4 promoter. PRRs also contribute to root hair development under phosphate-deficient and salt-stress conditions. Together, these findings establish a molecular framework in which PRR proteins regulate the RHD6/RSL network to coordinate root hair development and environmental responses.

Arabidopsis↗

PubMed2026

Does Timing Matter? Age of First Mobile Phone Acquisition and Psychological Outcomes in Middle and Late Adolescence.

The age at which adolescents acquire their first smartphone has decreased markedly in recent years; however, evidence on its long-term effects on psychosocial adjustment remains limited. This study investigated whether age at first mobile phone acquisition is associated with psychosocial functioning in middle and late adolescence, including social integration and competence, emotion regulation difficulties, disordered eating behaviors and problematic social media use (PSMU). The sample comprised 1179 adolescents aged 15-17 years (53.8% female). Linear regression and generalized additive mixed models were used to examine both linear and nonlinear associations, adjusting for age, gender and school clustering. Earlier smartphone acquisition was linearly but weakly associated with greater emotion regulation difficulties, disordered eating and PSMU, even after adjustment for covariates. In contrast, associations with social integration and competence were nonlinear: acquiring a first smartphone between ages 6 and 10 or after age 13 was associated with lower social integration in adolescence, whereas acquisition between ages 11 and 13 was linked to higher social functioning. These findings suggest that the developmental timing of first smartphone access shows a modest association with subsequent psychosocial functioning during middle and late adolescence. Focusing on the timing of access, alongside other demographic and contextual factors, may contribute to a better understanding of digital influences on adolescent well-being.

Humans↗

PubMed2026

Feasibility of Prone Positioning in Patients With Obesity and Acute Respiratory Distress Syndrome.

BACKGROUND: Prone positioning in patients with obesity remains uncommon because of concerns about feasibility, safety, and efficacy. OBJECTIVE: To evaluate the feasibility, safety, and clinical outcomes of manual prone positioning in patients with acute respiratory distress syndrome (ARDS) across different classes of obesity. METHODS: This was a retrospective cohort study involving patients with ARDS who underwent manual prone positioning across 15 hospitals between April 2014 and July 2024. Patients were stratified into 5 groups based on body mass index. Standardized prone positioning protocols were followed across institutions. RESULTS: A total of 1448 patients with ARDS underwent prone positioning. Across all obesity categories, prone positioning was associated with shorter intensive care unit and hospital stays, improved oxygenation, and better clinical outcomes. Notably, patients with class III obesity showed the greatest increase in gas exchange efficiency, with a 37% improvement in ratio of Pao2 to fraction of inspired oxygen, compared with 28% in patients with normal weight (P < .05). Complication rates were low across all groups. CONCLUSIONS: Prone positioning is feasible and safe in patients with ARDS across all obesity classes. Patients with class III obesity showed the greatest improvements in oxygenation. Future prospective studies should further explore the long-term impact of prone positioning in patients with class III obesity to refine clinical guidelines and optimize care.

Humans↗

PubMed2026

Differences in Radiological Risk Perceptions Following Online and In-Person Workshops.

Nuclear energy is widely regarded as a critical part of the pathway toward a secure, low-carbon electricity grid, yet long-term management of used nuclear fuel remains a persistent challenge. Although technically viable options for interim and consolidated storage exist, public concern and community opposition - rooted in historical distrust and risk perception - continue to complicate siting decisions. In response, recent federal efforts have emphasized collaboration-based approaches and community engagement, though empirical evidence on the effectiveness of different engagement strategies remains limited. This study examines how the structure and delivery of community engagement influence changes in public attitudes toward hosting interim used nuclear fuel storage facilities. Using survey data from 13 educational workshops around the United States, we evaluate: (1) the inclusion of trust-building content prior to technical content, and (2) engagement format, comparing online and in-person workshops. Analyses focus on participant changes in perceptions of safety, risk, and support for hosting, using the Wilcoxon rank-sum test and other non-parametric hypothesis tests on surveys conducted before and after workshops. Results indicate that workshop participation is associated with some measurable attitude changes, with significant (p < 0.05) differences in response variability for some questions across workshop formats. In particular, when comparing nuclear energy to other clean energy sources, in-person workshop participants are substantially more likely to gain a more favorable opinion of nuclear energy than online participants. These findings contribute empirical evidence on how trust-building and delivery mode shape outcomes in public engagement on complex and contested energy policy issues such as storage of used nuclear fuel.

nuclear fuel cycle↗

PubMed2026

Empathic Accuracy and Behavioral Empathy After a Moderate Dose of Beer.

OBJECTIVES: Empathic accuracy (EA) represents a person's ability to correctly infer the emotions of another person. One past study in men found lower EA for positive emotions after a moderate dose of hard liquor compared to after placebo, particularly among non-hazardous drinkers. The present study aimed to replicate this finding, using a moderate dose of beer and a mixed design. Moreover, we added a novel measure of behavioral empathy. METHODS: Participants (62% men) completed the Alcohol Use Disorders Identification Test, Empathy Quotient, and Revised Drinking Motives Questionnaire. Before and after drinking either beer (6.6% alcohol, n = 28) or its 0.0% equivalent (placebo, n = 38), they watched videoclips of targets talking about emotional autobiographical events and rated how targets felt while talking. Behavioral empathy was assessed by presenting participants with painful scenarios and asking whether they would help the people in pain. RESULTS: The previous finding of lower EA for positive emotions after alcohol was not replicated. Nonetheless, after alcohol non-hazardous drinkers were less willing to help people in pain. Trait affective empathy (i.e., a person's long-term disposition to experience emotional responses congruent to another's feelings) and the drinking to cope motive did not significantly moderate the findings. CONCLUSIONS: Although alcohol may alter empathy, its effects are not consistent and may depend on the dose and type of alcohol consumed. The moderating roles of trait empathy and trait aggressivity deserves further study.

Humans↗

PubMed2026

The Incidence of Suicide Following Metabolic and Bariatric Surgery: A Prognosis Systematic Review and Meta-Analysis of Longitudinal Studies.

BACKGROUND: Metabolic and bariatric surgery (MBS) effectively manages severe obesity but may lead to psychological complications such as completed suicides and suicide attempts. This review aimed to analyze suicide and self-harm incidence post-MBS. METHODS: We searched MEDLINE, EMBASE, PsycINFO, and the Cochrane Library databases on August 16, 2022, for longitudinal studies with incidence data on suicide following MBS. We performed a single proportion meta-analysis on the incidence of outcomes and assessed the certainty of evidence using the GRADE approach. The review was registered with PROSPERO (CRD42022352137). RESULTS: Eighty-four studies were included. The meta-analysis showed an incidence of 230.64 suicides per 100,000 participants (95% CI: 167.51 to 317.49) in pooled individual-level data and an incidence of 43.02 suicides per 100,000 person-years (95% CI: 32.49 to 56.97) in pooled person-year data. Evidence was low certainty or very low certainty. CONCLUSIONS: The average suicide incidence (231 per 100,000 people) in people with obesity who underwent MBS significantly exceeded the 2019 WHO global estimate for the general population (nine per 100,000 people). These findings underscore the need to incorporate structured psychological screening and follow-up into the perioperative management process of MBS, as patient mental health may play a pivotal role in postoperative adherence and long-term outcomes.

Humans↗

PubMed2026

Reference genome of the Californian trapdoor spider Aptostichus stephencolberti Bond 2008 (Araneae: Mygalomorphae: Euctenizidae).

We present a reference genome assembly for the trapdoor spider Aptostichus stephencolberti. This species, described in 2008, is endemic to the highly fragmented coastal dune habitats of Northern California from Monterey to the San Francisco Bay Area. Trapdoor spiders are ideal taxa for landscape scale genomic studies owing to their extreme site fidelity and limited dispersal capabilities; these same characteristics make them prone to extinction. Genomic studies of species like A. stephencolberti can reveal novel areas of endemism and high conservation value that may not be evident in species with wider ranges and greater dispersal capabilities. As part of the California Conservation Genomics Project, we constructed the A. stephencolberti reference genome from high quality long-read sequences, scaffolded with proximity ligation Omni-C data. The primary assembly comprises 551 scaffolds spanning 3.63 Gbp, a scaffold N50 of 62.2 Mbp and BUSCO completeness of 95.6%. We estimate 52 chromosomes yet find no (TTAGG)n telomer repeats. Expanding the telomeric repeat search finds an ancestral loss of the repeat from all spiders. Automated annotation using the NCBI refseq pipeline and RNAseq data from whole adults finds 14,067 genes with a BUSCO annotation completeness of 95.56%. Repeat annotation identified 77% of the genome to be interspersed repeats. This resource, the first for family Euctenizidae will facilitate future study and resulting conservation actions of A. stephencolberti and other Aptostichus sp. populations associated with the rapidly changing California coastal dune ecosystem.

Aptostichus stephencolberti↗

PubMed2025

Impacts of Climate Change and Related Weather Events on the Health and Wellbeing of Culturally and Linguistically Diverse Communities: A Systematic Review.

BACKGROUND: Vulnerable populations such as culturally and linguistically diverse communities (CALD), ethnic minorities and racial groups face a disproportionate burden of climate change-related health impacts due to a combination of socio-cultural and economic factors, geographic vulnerabilities and health disparities. This review synthesised the existing evidence on the health and wellbeing impacts of climate change and related weather events among CALD communities. METHODS: A narrative synthesis approach was utilised to conduct a systematic review. Three electronic databases (PubMed, Scopus and Web of Science) were searched, identifying 25 studies for appraisal and synthesis. Studies published in the English language from January 2010 to March 2024 were included in the review. RESULTS: The reviewed studies, mostly carried out in the USA, employed varied study designs, and focused on diverse CALD groups such as migrants, farmworkers and racial and ethnic minorities. The included studies addressed broader and specific climate change-related events, ranging from heat-related impacts and hurricanes to occupational heat exposure. CALD communities were found to be more vulnerable to climate change-related negative physical and mental health issues, further exacerbated by poor living conditions, limited access to healthcare, and cultural and language barriers. CONCLUSION: Future efforts by governments, healthcare agencies, employers and research institutions should prioritise multilingual risk communication strategies, providing culturally appropriate health education and healthcare access, housing improvements and the investigation of long-term health impacts of climate change and coping mechanisms adopted among CALD populations.

Climate Change↗

PubMed2026

A systematic review of macaque brain stimulation: Trends and future directions.

Neurostimulation techniques can powerfully modulate neural circuit activity and provide causal insights into the relationship between brain function and behavior. Macaque monkeys have long been a key animal model for brain stimulation studies. While stimulating the macaque brain with one or a few electrodes has already taught us much about brain function and dysfunction, recent technological advances promise a future with more precise stimulation using many more electrodes. However, such possibilities also increase the number of choices an experimenter has when designing their study. We can learn from a rich past, but a comprehensive overview of which brain regions have been studied and with what stimulation parameters is lacking. Here, we present a PRISMA-compliant systematic review of 734 macaque brain stimulation studies using electrical and/or optogenetic stimulation. We find a striking bias in which brain areas have traditionally been stimulated: a mere 10 brain regions account for half of all studies, with the remainder of studies investigating approximately 150 other areas. Across studies, stimulation frequency robustly predicted direct behavioral effects independent of brain region, while amplitude did not. Future studies could more systematically explore less studied regions through lower stimulation frequencies (e.g., 20-50 Hz) alongside established ranges (∼200 Hz). Tools such as fMRI or optical imaging can capture neural circuit engagement evoked by these frequencies, even when behavioral effects are absent or remain subtle. Our synthesis offers a guide towards the next steps in high-channel-count, high-precision stimulation approaches.

Animals↗

PubMed2026

Effects of strength and balance training on the structure of the aging brain.

BACKGROUND: While it is established that motor training induces structural changes in the brains of young adults, structural adaptations in aging brains are less studied. METHODS: This randomized controlled study investigated the impact of long-term strength and balance training on the structural plasticity in 60 elderly adults (64 - 82 years old, 70.6 ± 4.7) using multi-modal neuroimaging. We compared the effects of three months of strength training to balance training of the same duration and to a passive control group. Voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) were used to assess grey matter (GM) and white matter (WM) plasticity. White matter tract integrity (WMTI) modelling was employed to explore the microstructural underpinnings of white matter alterations. RESULTS: We found that strength training was associated with changes in diffusion metrics consistent with white matter microstructural remodeling, specifically increased extra-axonal axial diffusivity in the bilateral inferior fronto-occipital and longitudinal fasciculi. Additionally, both balance and strength training mitigated reductions in axonal water fraction in the splenium of the corpus callosum and the right posterior corona radiata observed in the control group. CONCLUSION: These results underscore the potential relevance of strength and balance training to induce beneficial neural plasticity by counteracting aging-related demyelination in the corpus callosum and highlight the specific role of strength training in facilitating white matter reorganization in key transmission fiber pathways.

Humans↗

PubMed2026

Chlorfenapyr-pyrethroid nets for pyrethroid-resistant malaria vectors: efficacy, resistance risks, and policy implications.

The Global Technical Strategy for Malaria 2016-2030 aims to reduce malaria incidence and mortality by 90%, yet widespread pyrethroid resistance among major malaria vectors in sub-Saharan Africa threatens this goal. Thus, the World Health Organization recommends chlorfenapyr-pyrethroid combination nets as a priority intervention where pyrethroid resistance undermines vector control. This systematic review synthesizes evidence on the performance, emerging resistance risks, and policy implications of these next-generation insecticide-treated nets. A structured search of literature from 2010 to 2024 across PubMed, Embase, WHO IRIS, and Google Scholar identified 31 eligible studies from 113 records. Evidence shows that chlorfenapyr-pyrethroid nets consistently outperform pyrethroid-only nets against resistant Anopheles populations, demonstrating a 1.8-fold increase in mosquito mortality (95% CI: 1.5-2.1). Community trials report 40-60% reductions in malaria infection incidence and entomological inoculation rates following deployment. However, early signs of chlorfenapyr resistance have emerged in Anopheles gambiae populations in Central Africa (RR: 2.4, p = 0.01), linked to CYP6P4 metabolic overexpression. A significant correlation was also observed between agricultural pesticide use and vector resistance patterns (r = 0.62, p < 0.05). Although chlorfenapyr-pyrethroid nets provide an important short-term tool for managing pyrethroid resistance, their long-term effectiveness depends on integrated resistance management. Rotational deployment with other insecticide classes, strengthened genetic and phenotypic surveillance, and a coordinated 'One Health' approach involving both public health and agriculture are essential to sustain gains and advance progress toward the 2030 malaria targets.

Pyrethrins↗

PubMed2026

Evidence of genome-wide relaxed selection on mildly deleterious mutations in an ancient subterranean catfish.

About one hundred subterranean catfish species have been described, resulting from repeated colonization of cave environments by multiple surface lineages. Most cave-dwelling species are found in the Americas, in particular in South America, but a few species also live in Central and North America. Despite the availability of high-quality genome assemblies for two cave species, the Mexican blind catfish Prietella phreatophila and the Colombian blind catfish Trichomycterus rosablanca, genomic approaches to investigate genetic changes associated with subterranean life or to estimate cave colonization times remain largely unexplored. To fill this gap, we additionally sequenced the genomes of four blind and depigmented subterranean catfishes from Peru (three Trichomycterus and one Astroblepus), as well as the genomes of four close surface relatives. We first extracted a large set of light-related genes, such as phototransduction and crystallin genes, and found contrasting decays of these sequences in different cave species, from 1% of pseudogenes in T. rosablanca to 48% in P. phreatophila. Two independent molecular dating methods gave congruent ages, indicating that these catfishes colonized subterranean habitats at different times, ranging from Early Pliocene to Late Pleistocene, supporting the hypothesis that surface catfishes repeatedly and rapidly adapted to subterranean habitats. The oldest cave species, P. phreatophila, appears to have been thriving in the dark for over 3.5 million years. Moreover, a genome-wide analysis of protein-coding genes suggests weaker purifying selection on mildly deleterious mutations in this cavefish than in other catfish lineages, likely reflecting a long-term small effective population size.

cavefishes↗

PubMed2026

Treating neurogenic detrusor overactivity in order to manage autonomic dysreflexia - A systematic review.

INTRODUCTION: Autonomic dysreflexia (AD) is a severe and potentially life-threatening complication of a spinal cord injury (SCI), particularly in patients with lesions at or above the sixth thoracic level. Neurogenic detrusor overactivity (NDO) is one of the main triggering factors. The impact of NDO treatment on AD remains insufficiently clarified. METHODS: We conducted a systematic review of the literature in PubMed and Cochrane Database between January 1990 and May 2025. Eligible studies included patients with SCI and AD undergoing treatment for NDO, including antimuscarinics, botulinum toxin (BTX) or augmentation cystoplasty. The primary outcome was the assessment of systolic blood pressure (SBP) parameters in patients undergoing cystomanometry. RESULTS: Of the thirteen eligible studies, only five were included. No study evaluated augmentation cystoplasty. One study (12 patients) evaluating fesoterodine and four studies (95 patients) evaluating BTX injection demonstrated improved urodynamic parameters and a decrease in severity of AD during urodynamic studies and in daily life. Improvements in AD-HR-QoL and I-QoL scores were also demonstrated. DISCUSSION: Controlling NDO with fesoterodine or BTX injection reduces the prevalence and severity of AD, likely by limiting abnormal C-fiber recruitment and reducing neurogenic inflammation. BTX additionally modulates TRPV1-expressing afferents, which further reduces AD risk. Although hypertensive peaks improve, submaximal parameters remain unchanged, highlighting the need for additional complementary strategies. CONCLUSION: The use of BTX and fesoterodine for NDO treatment effectively reduces AD episodes in patients with SCI. Further long-term studies are needed to confirm the cardiovascular benefits and inform future therapeutic strategies.

Humans↗

PubMed2026

Efficient rDNA-mediated multi-copy integration of gene clusters in Aureobasidium melanogenum.

Aureobasidium melanogenum is a promising non-conventional yeast chassis for synthetic biology. However, techniques recombining large genetic fragments, such as gene clusters, are still unavailable, hindering further metabolic reprogramming in this chassis. To achieve multi-copy integration of genes, we employed highly repetitive ribosomal DNA (rDNA) sequences in A. melanogenum as homologous recombination sites for large genetic fragments. First, integration efficiency of three different regions of A. melanogenum rDNA were investigated: RNA polymerase I promoter region (rDNA1, 1.0 kb), partial 26S rDNA region (rDNA2, 1.0 kb), and RNA polymerase I terminator region (rDNA3, 1.0 kb). Our findings revealed that the highest copy numbers and expression stability were observed for the short heterologous green fluorescent protein gene (gfp, 0.7 kb) and the long native polyketide synthase gene (pks, 7.0 kb) after rDNA1-mediated integration. Specifically, the copy numbers reached 7.0 and 8.0 for gfp and pks, respectively, and they remained stably expressed in the genome after 120-h subculturing. Furthermore, an 11.0 kb gene cluster (comprising the native pks, phosphopantetheinyl transferase (npg1), and scytalone dehydratase genes (scd) responsible for melanin biosynthesis) was integrated at the rDNA1 site, resulting in stable recombination with 15.0 copies and an approximately 12-fold increase in melanin production. Overall, the convenience and efficiency of the proposed rDNA-mediated multi-copy insertion strategy will facilitate superior metabolic engineering of A. melanogenum chassis cells.

Multigene Family↗