Gunes Ozhan

Premature ovarian insufficiency (POI), characterized by ovarian dysfunction before age 40, remains idiopathic in over 50% of cases, underscoring the urgent need to elucidate its genetic underpinnings. Here, we report a consanguineous Iranian family with five females diagnosed with POI, exhibiting elevated gonadotropins, undetectable anti-Müllerian hormone, and bilateral ovarian atrophy. Whole Exome Sequencing identified a novel homozygous missense variant in BIRC6 (NM_016252.4: c.11266C > T; p.Arg3756Cys), a gene encoding an apoptosis regulator. Segregation analysis confirmed an autosomal recessive inheritance pattern, with homozygosity exclusively in affected individuals. Functional studies in a CRISPR/Cas9-generated birc6 ^del12 zebrafish model recapitulated POI phenotypes: homozygous females exhibited reduced fecundity, aberrant oocyte morphology, and elevated embryonic death. Transcriptional analysis revealed dysregulation of apoptotic ( badb , sortilin , apc ) and fertility-related ( nanos1 , vtg1 ) genes, alongside unaltered estradiol levels, implicating apoptosis-driven follicular atresia rather than endocrine dysfunction. Compensatory increase in egg production in mutants mirrored human POI progression, where initial irregular cycles culminate in follicular depletion. This study establishes BIRC6 as a novel POI candidate, links its anti-apoptotic function to ovarian homeostasis, and highlights zebrafish as a tractable model for dissecting POI mechanisms. Our findings expand the genetic landscape of infertility and suggest therapeutic potential for apoptosis modulation in fertility preservation.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory impairment, and behavioral alterations. The pathogenesis of AD involves the accumulation of amyloid‐beta (Aβ) plaques and the hyperphosphorylated tau proteins, which disrupt neuronal function and trigger neuroinflammation. This study explores the therapeutic potential of epigallocatechin gallate (EGCG) and punicalagin (PU) in mitigating Aβ‐induced toxicity using an adult zebrafish model of AD. Our results demonstrate that the EGCG + PU combination significantly reduces Aβ accumulation, protects against cellular damage, suppresses acetylcholinesterase (AChE) activity, and normalizes the expression of amyloidogenic and AD‐related genes. Additionally, EGCG + PU treatment alleviates neuroinflammation by suppressing glial activation, including reductions in L‐plastin and proinflammatory cytokine expression, while promoting neuronal recovery through mechanisms of neurogenesis and neuroprotection. Notably, the combination treatment restored neuronal density and improved behavioral outcomes by alleviating anxiety‐ and aggression‐like behaviors associated with Aβ toxicity. These results underscore the synergistic neuroprotective effects of EGCG + PU, highlighting their potential as a novel therapeutic approach for mitigating the pathological, behavioral, and inflammatory aspects of AD.

Alzheimer’s disease (AD) is a complex neurodegenerative condition involving β-amyloid (Aβ) deposition, tau abnormalities, neuroinflammation, neuronal degeneration, and progressive impairment of cognitive functions. Despite extensive research, effective disease-modifying therapies remain limited, highlighting the need for translationally relevant models and repurposable therapeutic candidates. Dexmedetomidine (DEX), an α2-adrenergic receptor agonist with known neuroprotective properties, was investigated in an adult zebrafish model of AD established through cerebroventricular administration of Aβ42. DEX treatment significantly reduced Aβ accumulation and was associated with reduced amyloidogenic gene expression, indicating transcriptional changes in amyloidogenic pathway-related genes. DEX attenuated neuroinflammation by reducing glial activation, lowering pro-inflammatory cytokine gene expression, and increasing expression of the anti-inflammatory gene il10 . Immunofluorescence assessment further demonstrated reduced astrogliosis and preserved neuronal marker integrity, as indicated by increased HuC/D levels. Interestingly, DEX attenuated Aβ-induced proliferative responses, characterized by decreased PCNA expression, while enhancing cleaved caspase-3 levels, suggesting changes in proliferation and apoptotic signaling under Aβ stress conditions. Behavioral assessments further demonstrated that DEX alleviated Aβ42-induced anxiety- and aggression-like behaviors, improving behavioral phenotypes in this model. Overall, these findings underscore the multi-level effects of DEX in modulating AD-related pathological features. As a clinically available agent, DEX represents a promising candidate for repurposing in neurodegenerative disease contexts. Further preclinical studies in mammalian models are warranted to validate its translational relevance and therapeutic potential.

Notum is a carboxylesterase enzyme that modulates extracellular signaling by hydrolyzing palmitoleoyl residues from proteins, thereby influencing key pathways involved in cell differentiation, survival, and proliferation. While notum1 expression has been identified in the brain, its role in adult neurogenesis remains poorly understood. Using the adult zebrafish brain as a model system, we demonstrate that the notum1a homolog is broadly expressed across various brain cell types but is absent in undifferentiated radial glial cells. Pharmacological inhibition of Notum activity with the small molecule inhibitor ABC99 stimulates activation of radial glial cells, leading to increased neurogenesis. A BrdU pulse-chase assay confirms that ABC99-induced proliferation enhances the production of mature neurons. Despite Notum’s established role in Wnt signaling, transcriptional analysis following ABC99 treatment reveals no sustained impact on Wnt pathway targets, suggesting that Notum may regulate neurogenesis through alternative mechanisms. Our findings highlight notum1a as a potential modulator of neural progenitor cell dynamics in the adult brain and suggest that targeting Notum could represent a novel therapeutic strategy for neurodegenerative conditions characterized by impaired neurogenesis.

Graphene oxide (GO) and carbon nanotube (CNT)‐based nanomaterials have attracted significant interest in various industrial and biomedical applications due to their unique physicochemical properties; however, concerns about their potential toxicity, especially when modified with additives like melamine (M), remain largely unresolved. This study investigates the toxicological effects and underlying mechanisms of graphene oxide‐melamine (GO‐M) and carbon nanotube‐melamine (CNT‐M) nanoparticles in zebrafish ( Danio rerio ) embryos and larvae. To this end, developmental toxicity, phenotypic and behavioral changes, as well as histopathological and immunofluorescence alterations, were evaluated following acute exposure to GO‐M and CNT‐M nanoparticles at concentrations of 5, 10, and 20 mg/L. Results showed that both nanoparticles delayed larval hatching, particularly at higher concentrations (10 and 20 mg/L). Malformations were observed at 20 mg/L in the GO‐M group and at 10 and 20 mg/L in the CNT‐M group. Additionally, significant changes in larval length and eye area were observed at all concentrations for both nanoparticles. Behavioral assessments revealed that CNT‐M exposure at 10 and 20 mg/L significantly impaired head sensorimotor reflexes, while all concentrations affected tail reflexes. In contrast, GO‐M exposure did not significantly alter sensorimotor responses. These findings suggest differential toxic mechanisms and neurobehavioral effects of GO‐M and CNT‐M nanoparticles during early zebrafish development.

BACKGROUND: Olive leaves are rich in bioactive compounds with potential health benefits; however, their limited bioavailability and stability hinder their effective utilization. Emerging technologies, nanocarrier‐based delivery systems, have shown promise in enhancing these properties. RESULTS: The optimal conditions for proniosome formulation were 50 rpm rotational speed and 35 °C, achieving 81.20 ± 0.80% encapsulation efficiency. Particle sizes ranged from 188.6 to 248.9 nm, with a zeta potential of ~−30 mV, indicating high stability and resistance to aggregation. Advanced instrumental analysis confirmed interactions between the extract and proniosome components. After 30 days at 4 °C, extract‐loaded proniosomes maintained better homogeneity and lower polydispersity index. Cytotoxicity studies showed that both the extract and its proniosomal form were nontoxic to HEK293T cells up to 200 μg mL ⁻¹ . In zebrafish assays, minimal larval mortality was observed up to 3200 μg mL ⁻¹ for the extract, while no mortality occurred up to 1600 μg mL ⁻¹ for the proniosomal extract, highlighting its improved safety profile. CONCLUSION: The findings from this research could contribute to the advancement of sustainable and health‐promoting food innovations by integrating cutting‐edge nanotechnology‐driven encapsulation strategies into plant‐based food formulations. © 2025 Society of Chemical Industry.

The search for novel therapeutic agents has led to increasing interest in natural products, driven by the recognition that they may offer safer and more sustainable alternatives to synthetic drugs. This study aims to fill the gap in knowledge regarding the biological activity and safety of the water extract of chestnut ( Castanea mollissima ) (chestnut), a plant species with a long history of use in traditional medicine, by conducting a comprehensive evaluation of its antioxidant, antidiabetic, and neuroprotective properties. This study presents a comprehensive analysis of the water extract of chestnut for the first time using various bioanalytical antioxidant methods. The extract's inhibitory effects on key enzymes like acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α‐glycosidase were evaluated due to their relevance in metabolic and neurodegenerative disorders such as diabetes and Alzheimer's disease. Developmental toxicity and cytotoxicity were assessed using zebrafish ( Danio rerio ) embryos to evaluate the extract's biological safety. The major phenolic compounds present in the extract were identified by liquid chromatography‐electrospray ionization tandem mass spectrometry (LC‐ESI‐MS/MS), revealing catechin, gallic acid, taxifolin, and epicatechin as the predominant constituents. Antioxidant capacity was determined through radical scavenging assays using 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH ^• ) and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS ^•+ ), alongside ferric (Fe ³⁺ ), cupric (Cu ²⁺ ), and Fe ³⁺ ‐TPTZ (ferric‐tripyridyltriazine) reducing power assays. The findings highlight the significant antioxidant, antidiabetic, and neuroprotective potential of the chestnut water extract, supporting its prospective use in pharmaceutical and nutraceutical applications.

Transfer RNAs (tRNAs) are small non-coding RNA molecules transcribed from tRNA genes. tRNAs cleaved into a diverse population tRNA fragments (tRFs) ranging in length from 18 to 40 nucleotides, they interact with RNA binding proteins and influence the stability and translation. Stress is one of the reasons for tRFs cleavage. In our study, we modeled oxidative stress conditions with hydrogen peroxide (H₂O₂) exposure and dealt with one of the frequently expressed tRF in the hippocampus region of the brain, which is tRF-Glu-CTC. For this purpose, neural stem cells (NSCs) were exposed to H₂O₂, and tRF-Glu-CTC levels were increased in various H₂O₂ concentrations. A decrease was seen in microtubule-associated protein 2 (MAP2) marker expression. To understand the H₂O₂ oxidative stress condition on the expression of tRNA fragments, 72 hpf zebrafish embryos exposed to different H₂O₂ concentrations, an increase in the level of tRF-Glu-CTC was observed in all concentrations of H₂O₂ compared to control. Subsequently, neurogenesis markers were figured out via Calb2a (calbindin 2a) in situ hybridization (ISH) and HuC/D immunofluorescence staining (IF) staining experiments. Under H₂O₂ exposure, a decline was observed in Calb2a and HuC/D markers. To understand the inhibitory role of tRF-Glu-CTC on neurogenesis, NSCs were transfected via tRF-Glu-CTC inhibitor, and neurogenesis markers (ßIII-tubulin, MAP2, and GFAP) were determined with qRT-PCR and IF staining. tRF-Glu-CTC inhibitor reversed the diminished neuronal markers expression under the exposure of H₂O₂. Gene Ontology (GO) enrichment analysis showed us that targets of tRF-Glu-CTC are generally related to neuronal function and synaptic processes.

The increasing use of nanotechnology, especially in agriculture and the food industry, has raised concerns about the possible adverse effects of nanomaterials (NMs) on human health and the environment. This study investigates the effects of synthesized graphene oxide (GO) and its derivatives on zebrafish exposed for 96 hr, focusing on morphological changes in brain tissue, histopathology, and immunofluorescent markers such as 8-hydroxy-2'-deoxyguanosine (8-OHdG) and nucleolar protein 10 (NOP10). Exposure to GO resulted in malformations, DNA damage, and increased NOP10 expression, and it reduced hatching and survival rates. Our results demonstrated that exposure to GO, graphene oxide-oxime (GO-OX), and OX exerted dose-dependent inhibitory effects on hatching and promoted malformations in zebrafish larvae. Histopathological analysis revealed that higher doses led to more pronounced tissue damage, with GO 50 causing severe degeneration and necrosis, while high doses of GO-OX and OX resulted in moderate tissue changes. This was further supported by the increased expression levels of 8-OHdG (marker of oxidative DNA damage) and NOP10 (marker of nucleolar stress), which aligns with the histopathological findings and confirms the neurotoxic effects. Notably, GO-OX treatments consistently mitigated both morphological and neurotoxic effects at all doses, suggesting that oxime functionalization reduces the inherent toxicity of GO. In contrast, treatment with different concentrations of GO-OX derivatives mitigated these adverse effects, reducing them to mild or moderate levels.

Epilepsy, the most common neurological disorder worldwide, is characterized by sudden paroxysmal brain activity, which can be generalized or focal. Extensive research has explored various treatment strategies for this condition. Our study employed a pilocarpine (PL)-induced seizure model in zebrafish (Danio rerio) embryos and larvae to assess the effects of carbamazepine (CBZ)-loaded chitosan-coated PLGA-Zein nanoparticles (NPs) over 96 hours. We evaluated the developmental toxicity (mortality, malformation, and larval hatching), behavioral changes (sensorimotor reflexes), and histopathological and immunohistochemical alterations in brain tissue, focusing on 5-hydroxytryptamine receptor 4 (5HT4), and brain and muscle ARNT-Like 1 (BMAL1) expressions. Our findings revealed high mortality and malformation rates in groups treated with pure CBZ (PL+CBZ 50 and PL+CBZ 100). These groups also exhibited delayed hatching and impaired sensorimotor reflexes. In contrast, the CBZ-NP-treated groups (PL+CBZ NP 50 and PL+CBZ NP 100) showed hatching rates comparable to the control group, with significantly lower mortality and malformation rates compared to pure CBZ-treated groups. Moreover, intense cytoplasmic expression of 5HT4 and BMAL1 was observed in neuropils of the PL+CBZ 100 group. This study highlights the potential of CBZ-loaded NPs in reducing developmental toxicity and adverse neurological effects associated with pure CBZ treatment in seizure models.