dUTPase is universally regarded as a metabolic sanitizing enzyme that protects genomes by preventing the incorporation of uracil into DNA. Despite its essentiality across eukaryotes, no function beyond nucleotide sanitization has been demonstrated. Here, we uncover a conserved, non-canonical role for dUTPase as a regulator of mitosis. Using Drosophila and mouse models, we demonstrate that dUTPase loss causes early embryonic lethality characterized by severe mitotic failure that, cannot be rescued by disabling uracil-DNA repair, uncoupling dUTPase essentiality from DNA repair pathways. Mechanistically, dUTPase dynamically associates with the mitotic spindle and centrosomes, and its depletion induces centrosome amplification and chromosome segregation defects. Beyond cell division, dUTPase dosage bidirectionally controls cell migration, linking its mitotic function to cellular behaviors relevant for metastasis. Together, our findings redefine dUTPase as a moonlighting mitotic factor that coordinates centrosome integrity and spindle dynamics, expanding its known repertoire beyond nucleotide metabolism. ### Competing Interest Statement The authors have declared no competing interest. National Research, Development and Innovation Office, K135231, K138318, K146890, FK137867, NKP-2018-1.2.1-NKP-2018-00005, 2022-1.2.2-TÉT-IPARI-UZ-2022-00003 Ministry for Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, TKP2021-EGA-02 ICGEB Research Grants Programme 2023, CRP/HUN23-02 Agribiotechnology and Precision Breeding for Food Security National Laboratory, RRF-2.3.1-21-2022-00007 Momentum Grant of the Hungarian Academy of Sciences, LP2023-15/2023 EMBO Installation Grant, IG5670-2024 HUN-REN Welcome Home and Foreign Researcher Recruitment Grant, KSZF-143/2023 Research Council of Norway through its Centres of Excellence, Project Number 33271 National Research Development and Innovation Fund of the Ministry of Culture and Innovation, Doctoral Excellence Fellowship Programme

MicroRNAs (miRNAs) are short, non-coding RNA molecules that play a crucial role in regulating various biological processes by influencing post-transcriptional gene expression and gene silencing. Background/Objectives: In this study, rabbit embryos were utilised as a model system to investigate potential biomarkers relevant to human embryo development. Seven microRNAs (miRNAs) identified in the embryo culture medium were evaluated as biomarkers by analysing the correlation between their expression levels and the developmental quality of rabbit embryos at days 4 and 6. Methods: We analysed the expression of seven development-specific miRNAs (miR-24-3p, miR-28-3p, miR-103a-3p, miR-181a-5p, miR-191-5p, miR-320a-3p, miR-378a-3p) in 4-day-old and 6-day-old rabbit embryos, along with their culture media. Results: Our findings revealed significant differences in the expression levels of these miRNAs between the 4-day-old and 6-day-old embryos. On the other hand, the expression patterns observed in the culture medium samples showed less variation between the two age groups. Nonetheless, analysis of miRNA expression profiles in the spent culture medium from individually cultured embryos enabled the identification of lower-quality embryos, characterised by smaller size and impaired or delayed development. Conclusions: The detection of these miRNAs in embryo culture medium may serve as a reliable indicator of successful progression to the blastocyst stage. Our experimental results identified specific miRNAs whose expression profiles differ according to embryonic stage and quality, thereby reflecting key developmental milestones. Notably, the detectability of these miRNAs in the medium—without prior RNA isolation—indicates their active secretion into the extracellular environment. By synthesising our findings with the existing literature, we refined a panel of miRNAs essential for the development of implantation-competent embryos in both rabbits and humans. Consequently, we developed a non-invasive assay for predicting implantation and pregnancy outcomes, which may have significant applications in human reproductive medicine.

The enzyme dUTPase has an essential role in maintaining genomic integrity. In mouse, nuclear and mitochondrial isoforms of the enzyme have been described. Here we present the isoform-specific mRNA expression levels in different murine organs during development using RT-qPCR. In this study, we analyzed organs of 14.5-day embryos and of postnatal 2-, 4-, 10-week- and 13-month-old mice. We demonstrate organ-, sex- and developmental stage-specific differences in the mRNA expression levels of both isoforms. We found high mRNA expression level of the nuclear isoform in the embryo brain, and the expression level remained relatively high in the adult brain as well. This was surprising, since dUTPase is known to play an important role in proliferating cells, and mass production of neural cells is completed by adulthood. Thus, we investigated the pattern of the dUTPase protein expression specifically in the adult brain with immunostaining and found that dUTPase is present in the germinative zones, the subventricular and the subgranular zones, where neurogenesis occurs and in the rostral migratory stream where neuroblasts migrate to the olfactory bulb. These novel findings suggest that dUTPase may have a role in cell differentiation and indicate that accurate dTTP biosynthesis can be vital, especially in neurogenesis.

Understanding the responses of animals to seasonal heat stress on the genomic level has led to the identification of genes implicated in thermal stress reaction mechanisms. In this study, the relative gene expression of Interleukin-10 (IL-10), an anti-inflammatory cytokine and biomarker for heat stress-mediated immune modulation, was observed during the summer and winter seasons in continental and tropical sheep breeds, namely, Hungarian Indigenous Tsigai and White Dorper, employing quantitative real-time polymerase chain reaction (qRT-PCR). Temperature-humidity indices (THI) were calculated to assess heat stress levels. The results indicate that IL-10 CT-values were significantly higher during the summer, when heat stress prevails, in both sheep breeds compared to winter. While the White Dorper exhibited a higher numerical value for the summer relative gene expression ratio (16.2) compared to the Hungarian Indigenous Tsigai (12.3), no significant differences in CT values were observed between breeds or among sexes. These findings suggest the immune-adaptive characteristics of the two sheep breeds during seasonal heat stress. The variation of IL-10 gene expression levels between the two breeds can be attributed to their geographical origins; the White Dorper emerging from arid subtropical South Africa and the Hungarian Indigenous Tsigai Sheep thriving in the seasonally harsh Carpathian climate for centuries.

The adverse effects of climate change on sheep farming have become more noticeable in recent decades. Extensive efforts have been made to untangle the complex relationship between heat tolerance, animal health, and productivity, also to identify a resilient and economically suitable breed for selection that can be resilient to future climate change conditions. Using quantitative real-time polymerase chain reaction (qRT-PCR), we observed the seasonal variations in the expression of several important genes related to heat stress and immunity (HSP70, IL10, TLR2, TLR4, and TLR8) in three of the most widely kept sheep breeds in Hungary: The indigenous Tsigai, Hungarian Merino, and White Dorper. We found that the seasonal stressor affected the relative gene expression of all genes in this study. Notably, The Hungarian indigenous Tsigai was the most robust breed adapted to the Hungarian continental (hot summer, cold winter) environment, with excellent thermotolerance and immunity. Furthermore, despite suffering from heat stress in the summer, Hungarian Merino maintained their robust immune system well throughout the year.

Nonrodent animal models have recently become more valuable in preclinical studies. The limitation of nonrodent animal models is that they must demonstrate relatively reliable and predictable responses in addition to representing complex etiologies of a genetically diverse patient population. In our study, we applied CRISPR/Cas9 technology to produce transgenic rabbits. This approach can be useful for creating genetically divergent and homogeneous populations for studies in translational medicine. NADPH oxidase 4 (NOX4) is a promising therapeutic target, as it is linked to several pathologies including stroke, atherosclerosis, and lung and kidney fibrosis. NOX4 knockout (KO) rabbit lines were created in order to study the in vivo effects resulting from a lack of NOX4 protein and loss of gene function. One of the knockout founders was a germline multiallelic knockout male. Its offspring segregated into three distinct NOX4 knockout and a wild-type lines. Mosaicism is a relatively frequent phenomenon in rabbit transgenesis. Our results point to the possible application of mosaicism in preclinical studies. However, careful planning and evaluation of results are necessary. The predicted off-target sites were studied as well, and no signs of off-target events were detected.

The coupling of nucleotide biosynthesis and genome integrity plays an important role in ensuring faithful maintenance and transmission of genetic information. The enzyme dUTPase is a prime example of such coupling, as it generates dUMP for thymidylate biosynthesis and removes dUTP for synthesis of uracil‐free DNA. Despite its significant role, the expression patterns of dUTPase isoforms in animals have not yet been described. Here, we developed a detailed optimization procedure for RT‐qPCR‐based isoform‐specific analysis of dUTPase expression levels in various organs of adult mice. Primer design, optimal annealing temperature, and primer concentrations were specified for both nuclear and mitochondrial dUTPase isoforms, as well as two commonly used reference genes, GAPDH and PPIA. The linear range of the RNA concentration for the reverse transcription reaction was determined. The PCR efficiencies were calculated using serial dilutions of cDNA. Our data indicate that organs involved in lymphocyte production, as well as reproductive organs, are characterized by high levels of expression of the nuclear dUTPase isoform. On the other hand, we observed that expression of the mitochondrial dUTPase isoform is considerably increased in heart, kidney, and ovary. Despite the differences in expression levels among the various organs, we also found that the mitochondrial dUTPase isoform shows a much more uniform expression pattern as compared to the reference genes GAPDH and PPIA.