Mammalian fertilization initiates the reprogramming of oocytes and sperm, forming a totipotent zygote. During this intricate process, the zygotic genome undergoes a maternal-to-zygotic transition (MZT) and subsequent zygotic genome activation (ZGA), marking the initiation of transcriptional control and gene expression post-fertilization. Histone modifications are pivotal in shaping cellular identity and gene expression in many mammals. Recent advances in chromatin analysis have enabled detailed explorations of histone modifications during ZGA. This review delves into conserved and unique regulatory strategies, providing essential insights into the dynamic changes in histone modifications and their variants during ZGA in mammals. The objective is to explore recent advancements in leading mechanisms related to histone modifications governing this embryonic development phase in depth. These considerations will be useful for informing future therapeutic approaches that target epigenetic regulation in diverse biological contexts. It will also contribute to the extensive areas of evolutionary and developmental biology and possibly lay the foundation for future research and discussion on this seminal topic.

Mammalian fertilization initiates the reprogramming of oocytes and sperm, leading to the formation of a totipotent zygote. The zygotic genome remains transcriptionally silent throughout this intricate process, undergoing the maternal-to-zygotic transition (MZT) and subsequent zygotic genome activation (ZGA). Histone modifications are pivotal in shaping cellular identity and gene expression in many mammals. Recent advances in chromatin analysis enable a detailed exploration of histone modifications during ZGA. This review delves into conserved and unique regulatory strategies, providing essential insights into the dynamic changes in histone modifications and their variants during ZGA in mammals. The objective is to explore recent advancements in leading mechanisms related to histone modifications governing this embryonic development phase in depth. These considerations will be useful for informing future therapeutic approaches that target epigenetic regulation in diverse biological contexts, ranging from regenerative medicine to cancer research. It will also contribute to the extensive areas of evolutionary and developmental biology and possibly lay the foundation for future research and discussion on this seminal topic.

Quantification of T‐cells, B‐cells, and NK‐cells assay is crucial for diagnosing and monitoring immune diseases and evaluating lymphodepleting therapies. To standardize and validate an optimized workflow of the Beckman Coulter DuraClone IM Phenotyping Basic Kit for quantification of TBNK subsets in peripheral blood. Procedural changes included the use of an alternative lysis buffer, the addition of counting beads, the elimination of centrifugation steps, and an increase in acquisition volume. Validation followed CLSI H42‐A2 and H62 guidelines, assessing accuracy, precision, linearity, and limit of quantification (LLOQ). Accuracy was evaluated by comparison with Immuno‐Trol controls and by Bland–Altman analysis against standard immunophenotyping methods. External proficiency was assessed through participation in the College of American Pathologists (CAP) TBNK program in 2024. Procedural steps were reduced by 50%, and processing time by 38.6%. The modified method demonstrated high accuracy (−3 < bias < 35; cells/μL), a low bias based on Immuno‐Trol targets, and strong agreement in the Bland–Altman analysis. The method successfully passed three CAP external proficiency tests in 2024, confirming interlaboratory reliability. Coefficients of variation for precision were below 10% for all subsets. Linearity exceeded R ² > 0.99 across clinically relevant ranges. Most subsets demonstrated an LLOQ below 10–50 cells/μL, which is suitable for clinical applications. The proposed modifications to the DuraClone IM kit protocol improved workflow efficiency and analytical performance without compromising accuracy or reproducibility. The validated method provides a standardized, reliable, and time‐efficient alternative for lymphocyte subset quantification.

Age-related changes in the immune system are called immunosenescence. Within the T lymphocytes is the subpopulation of double negative (DNT) peripheral lymphocytes that are immunomodulators of the immune response, based on their ability to suppress the functions of simple positive T cells and their cytotoxicity for tumor cells and those infected by viruses. To determine the frequency of peripheral DNT lymphocytes in older Cuban adults. A cross-sectional study was carried out in 30 older adults, residents in Cuba. DNT lymphocytes in peripheral blood were quantified by flow cytometry. A Beckman Coulter Gallios flow cytometer was used for data reading and analysis. Percentage values mean and standard deviation were used. The Chi-square was used to relate the percentage values of DNT and comorbidities. It was considered statistically significant if p ≤ 0.05. There was a predominance of women who represented 70 %. No older adult with low values of DNT lymphocytes was reported. Women with high percentage and absolute values of DNT lymphocytes prevailed in relation to men. In the group ≥80 years, high values in % and absolute values of DNT lymphocytes predominated. The high percentage values of DNT cells were mainly related to cardiovascular disease, and predominated in the elderly of ≥80 years old; who presented respiratory and skin infections, fundamentally. The percentage normal value in the group < 80 years was significant (p = 0.0198). The Chi-square value was 0,5995. Most older adults who exhibited high percentage and absolute values of DNT lymphocytes, or a tendency to them, had some associated comorbidity, an idea that suggests that DNT cells participate in immune surveillance, defense and homeostasis based on their double identity, that is, its pathogenic or immunosuppressive phenotype according to the specific immunological microenvironment.