Non-coding RNAs and chromatin: key epigenetic factors from spermatogenesis to transgenerational inheritance.

Cellular fate and gene expression patterns are modulated by different epigenetic factors including non-coding RNAs (ncRNAs) and chromatin organization. Both factors are dynamic throughout male germ cell differentiation on the seminiferous tubule, despite the transcriptional inactivation in the last stages of spermatogenesis. Sperm maturation during the caput-to-cauda transit on the epididymis involves changes in chromatin organization and the soma-to-germ line transference of ncRNAs that are essential to obtain a functional sperm for fertilization and embryo development. Here, the male environment (diseases, drugs, mental stress) is crucial to modulate these epigenetic factors throughout sperm maturation, affecting the corresponding offspring. Paternal transgenerational inheritance has been directly related to sperm epigenetic changes, most of them associated with variations in the ncRNA content and chromatin marks. Our aim is to give an overview about how epigenetics, focused on ncRNAs and chromatin, is pivotal to understand spermatogenesis and sperm maturation, and how the male environment impacts the sperm epigenome modulating the offspring gene expression pattern.

Changes in sperm function and structure after freezing in domestic cat spermatozoa.

Sperm cryopreservation allows for a long-term storage of genetic. However, changes due to factors as cold shock, osmotic and oxidative stress cause reduction in viability and fertilising ability of frozen/thawed spermatozoa. Therefore, evaluation of cryoinjury of cat spermatozoa is a key factor in achieving better cryopreservation results. This study analysed the changes in structural and functional after freezing in ejaculated domestic cats spermatozoa. Semen samples (n = 60) were analysed before and after freezing, progressive motility was determined with computer-assisted sperm analysis and viability, and acrosome intact spermatozoa, mitochondrial function and superoxide anion ( O 2 - ) were assessed by flow cytometry. The results demonstrated that cryopreservation induced changes in all sperm parameters (p < 0.05). Total sperm motility, viability, acrosome integrity and mitochondrial function of fresh samples were near to 80% and decrease near to 40% in frozen/thawed spermatozoa (p < 0.05); nevertheless, in contrast to all other sperm parameters, the sperm positive with O 2 - increased post/thawing (p < 0.05). In conclusion, changes in frozen/thawed spermatozoa could be related to the effect of oxidative stress due to the increase in the synthesis of O 2 - and a concomitant loss of functional competence. Therefore, the evaluation of these sperm parameters could contribute to complement the analysis of fresh or frozen semen used ART.

Melatonin Scavenger Properties against Oxidative and Nitrosative Stress: Impact on Gamete Handling and In Vitro Embryo Production in Humans and Other Mammals.

Oxidative and nitrosative stress are common problems when handling gametes in vitro. In vitro development in mammalian embryos is highly affected by culture conditions, especially by reactive oxygen species (ROS) and reactive nitrogen species (RNS), because their absence or overproduction causes embryo arrest and changes in gene expression. Melatonin in gamete co-incubation during in vitro fertilization (IVF) has deleterious or positive effects, depending on the concentration used in the culture medium, demonstrating the delicate balance between antioxidant and pro-oxidant activity. Further research is needed to better understand the possible impact of melatonin on the different IVP steps in humans and other mammals, especially in seasonal breeds where this neuro-hormone system highly regulates its reproduction physiology.

Revealing the associated microflora hosted by the globally significant parasite Trichostrongylus colubriformis.

Trichostrongylus colubriformis is a parasitic helminth that primarily infects small ruminants, causing substantial economic losses in the livestock industry. Exploring the microbiome of this helminth might provide insights into the potential influence of its microbial community on the parasite's survival. We characterised the intestinal microbiome of T. colubriformis that had been collected from the duodenum of sheep, and compared the helminth microbiome with the duodenal microbiome of its host, aiming to identify contributions from the helminth's environment. At the same time, we explored the isolation of fastidious organisms from the harvested helminth. Primary alpha and beta diversity analyses of bacterial species revealed statistically significant differences between the parasite and the host, in terms of species richness and ecological composition. 16S rRNA differential abundance analysis showed that Mycoplasmoides and Stenotrophomonas were significantly present in T. colubriformis but not in the duodenal microbiome of the sheep. Furthermore, two bacteria, Aeromonas caviae and Aeromonas hydrophila, were isolated from T. colubriformis. Examinations of the genome highlight differences in genome size and profiles of antimicrobial resistance genes. Our results suggest that T. colubriformis carries a specific bacterial community that could be supporting the helminth's long-term survival in the host's digestive system.

Non-coding RNAs and chromatin: key epigenetic factors from spermatogenesis to transgenerational inheritance

Cellular fate and gene expression patterns are modulated by different epigenetic factors including non-coding RNAs (ncRNAs) and chromatin organization. Both factors are dynamic throughout male germ cell differentiation on the seminiferous tubule, despite the transcriptional inactivation in the last stages of spermatogenesis. Sperm maturation during the caput-to-cauda transit on the epididymis involves changes in chromatin organization and the soma-to-germ line transference of ncRNAs that are essential to obtain a functional sperm for fertilization and embryo development. Here, the male environment (diseases, drugs, mental stress) is crucial to modulate these epigenetic factors throughout sperm maturation, affecting the corresponding offspring. Paternal transgenerational inheritance has been directly related to sperm epigenetic changes, most of them associated with variations in the ncRNA content and chromatin marks. Our aim is to give an overview about how epigenetics, focused on ncRNAs and chromatin, is pivotal to understand spermatogenesis and sperm maturation, and how the male environment impacts the sperm epigenome modulating the offspring gene expression pattern.

Modulación del estado de óxido-reducción por peróxido de hidrógeno en la etapa de maduración ovocitaria: efecto sobre el desarrollo embrionario en bovinos / Modulation of redox state by hydrogen peroxide in the stage of oocyte maturation: effect on embryonic development in cattle

El estrés oxidativo es definido como un desbalance entre la producción de oxidantes y antioxidantes. La inducción de tolerancia a estrés en los ovocitos conllevaría a un mejor desarrollo embrionario. En bovinos, la incubación de ovocitos maduros con diferentes estresores (térmicos, alta presión hidrostática, oxidativos) incrementaría la tasa de generación de blastocitos. Este estudio evalúa el efecto de la modulación del estado redox incrementando el estrés oxidativo con H2O2 en ovocitos maduros bajo condiciones de cultivo in vitro y su efecto sobre el potencial de desarrollo embrionario. Para ello, ovocitos procedentes de ovarios de matadero fueron madurados en medio TCM-199 suplementado durante 22­23 h, a 38,5 °C, 5 % CO2 y humedad a saturación. Al final de las 22­23 h se incubaron los ovocitos maduros con 0, 50, 100 y 200 µM H2O2. La fecundación in vitro se realizó co-incubando los ovocitos durante 18 h con una concentración final de 1x106 espermatozoides/mL. Los presuntos cigotos fueron denudados y cultivados en medio KSOM-0,4 % BSA a 38,5 °C en atmósfera de baja tensión de O2 (5 % O2, 5 % CO2 y 90 % N2) y humedad a saturación. El estrés oxidativo inducido con H2O2 a una concentración de 50 y 100 µM produce una tasa de división de los embriones similar al control (88,7 %, 83,2 % y 86,4 % respectivamente, p>0,05), disminuyendo significativamente al utilizar una concentración de 200 µM (58,8 %, p<0,05). Asimismo, H2O2 causó un efecto similar en la tasa de blastocitos con 50 µM (20,4 % vs. 25,8 % control, p>0.05) pero disminuyó significativamente con 100 y 200 µM (10,7 % y 3,3 % respectivamente, p<0,05). Es posible, que estos embriones resistentes al estrés oxidativo puedan tener una mayor sobrevida durante los procesos de criopreservación que generan altos niveles de especies reactivas de oxígeno en los embriones.

Oxidative stress is defined as an imbalance between the production of oxidants and antioxidants. The induction of stress tolerance in oocytes leads to a better embryonic development. In cattle incubating mature oocytes with different stressors (thermal, high hydrostatic pressure, oxidative) increase the generation rate of blastocysts. The purpose of this study was to evaluate the effect of modulating the redox state increasing the oxidative stress through H2O2 in mature oocyte under in vitro culture conditions and its effect on the potential of embryonic development. To do this, oocytes from slaughterhouse ovaries were matured in TCM-199 medium supplemented for 22­23 h at 38.5 °C, 5 % CO2 and humidified atmosphere. At the end of 22­23 h, the treatments with 0, 50, 100 and 200 µM H2O2 were applied for 1 h. IVF was performed co-incubating the eggs for 18 h with a final concentration of 1x106 sperm/mL. The presumptive zygotes were denuded and cultured in medium KSOM-0.4 % BSA to 38.5 °C in an atmosphere of low concentration of O2 (5 % O2, 5 % CO2 and 90 % N2) and humidified atmosphere. The results show that the induction of oxidative stress by H2O2 produces a similar effect using a concentration of 50 and 100 mM in the cleavage rate of embryos compared to control (88.7 %, 83.2 % and 86,4 % respectively, p>0.05) and decreasing significantly by using a concentration of 200 mM (58.8 %, p<0.05). Also, H2O2 caused a similar effect on the rate of blastocysts with 50 µM (20.4 % vs. 25.8 control, p>0.05) but decreased significantly with 100 and 200 µM (10.7 % and 3.3 % respectively, p<0.05). It is possible that these embryos resistant to oxidative stress may have a higher survival in the cryopreservation processes that generating high levels of reactive oxygen species.