Rainbow trout (Oncorhynchus mykiss) is a promising cultivable fish species with significant potential for expansion. As a cold-water fish belonging to the Salmonidae family, it requires an optimal temperature range of 10–15°C for optimal growth. This study explores a method for producing sterile rainbow trout with maximum survival rates by using heat shock treatment to enhance growth characteristics and improve aquaculture practices. A control group and four heat shock treatments were given at 26°C and 28°C for 10 min, applied 15 and 20 min after the mixing of eggs and milt, using a water bath. Among the treated groups, the highest fertilisation, hatching and yolk sac absorption rates were 90.3 ± 0.3%, 81.8 ± 0.8% and 83.9 ± 0.5%, respectively. The highest triploidy rate of 76.6 ± 3.3% was observed with a heat shock at 28°C, 20 min after fertilisation. In contrast, none of the fish from the control group were triploids. The control group demonstrated higher survival rates at fertilisation (93.1 ± 0.4%), hatching (84.2 ± 0.4%) and complete yolk sac absorption (86.2 ± 0.5%) compared to the heat-shocked groups. The diploid and triploid chromosome numbers in rainbow trout were determined to be 2n = 60 and 3n = 91, respectively. This study confirms that heat shock treatment can effectively induce triploidy in rainbow trout, with significant variations in triploidy rates depending on the temperature and timing of the shock. While heat shock can enhance the production of sterile fish, it is essential to balance the treatment parameters to maintain high survival rates. These findings contribute to the optimisation of triploidy induction techniques and support the advancement of aquaculture practices by improving the growth, management and survival rates of rainbow trout which could significantly benefit aquaculture efficiency and sustainability.

Treatment with follicle-stimulating hormone (FSH) and testosterone (T2) and their combination have been observed to be influential on ovarian follicles of 1-day-old mice ovaries cultured for 8 days. Given that extension of the culture period could positively impact the development of follicles in cultured ovaries, the present study was conducted to evaluate the main and interaction effects of FSH by T2 on the development of ovarian follicles in 1-day-old mice ovaries cultured for 12 days. One-day-old mice ovaries were initially cultured with base medium for 4 days; thereafter, different hormonal treatments were added to the culture media, and the culture was continued for 8 additional days until day 12. Ovaries were collected for histological and molecular assessments on day 12. The greatest activation of primordial follicles and progression of activated follicles to the preantral stage was detected in ovaries treated with the combination of FSH and T2 (P < 0.05). This positive effect on the morphology of ovarian follicles was accompanied by upregulation of Pi3k, Gdf9, Bmp15, Cx37 and Fshr in the ovaries cultured with the combination of FSH and T2 (P < 0.05). Nonetheless, treatment with FSH and T2 led to a diminished proportion of intact follicles (P < 0.05), even though Bax/Bcl2 gene expression ratio, as an apoptotic index, was less in hormone-treated ovaries (P < 0.05). In conclusion, the combination of FSH and T2 could improve the activation of primordial follicles and the growth of activated follicles towards the preantral stage. This positive effect of FSH plus T2 appeared to be at least partly mediated through the upregulation of Pi3k and oocyte-derived growth factors including Gdf9 and Bmp15.

This study aimed to demonstrate the utilization value of 1PN embryos. The 1PN zygotes collected from December 2021 to September 2022 were included in this study. The embryo development, the pronuclear characteristics, and the genetic constitutions were investigated. The overall blastocyst formation and good-quality blastocyst rates in 1PN zygotes were 22.94 and 16.24%, significantly lower than those of 2PN zygotes (63.25 and 50.23%, respectively, P = 0.000). The pronuclear characteristics were found to be correlated with the developmental potential. When comparing 1PN zygotes that developed into blastocysts to those that arrested, the former exhibited a significantly larger area (749.49 ± 142.77 vs. 634.00 ± 119.05, P = 0.000), a longer diameter of pronuclear (29.81 ± 3.08 vs. 27.30 ± 3.00, P = 0.000), and a greater number of nucleolar precursor body (NPB) (11.56 ± 3.84 vs. 7.19 ± 2.73, P = 0.000). Among the tested embryos, the diploidy euploidy rate was significantly higher in blastocysts in comparison with the arrested embryos (66.67 vs. 11.76%, P = 0.000), which was also significantly higher in IVF-1PN blastocysts than in ICSI-1PN blastocysts (75.44 vs. 25.00%, P = 0.001). However, the pronuclear characteristics were not found to be linked to the chromosomal ploidy once they formed blastocysts.

In summary, while the developmental potential of 1PN zygotes is reduced, our study shows that, in addition to the reported pronuclear area and diameter, the number of NPB is also associated with their developmental potential. The 1PN blastocysts exhibit a high diploidy euploidy rate, are recommend to be clinically used post genetic testing, especially for patients who do not have other 2PN embryos available.

In vitro production of porcine embryos is a complicated process that includes in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro culture (IVC). Insufficient cytoplasmic maturation, slow zona reaction and improper embryo culture conditions will compromise the efficiency of porcine embryo production in vitro. Previous studies have shown that insulin-transferrin-selenium (ITS) in IVM or IVC medium could improve porcine oocyte maturation, decrease polyspermy fertilization and promote subsequent embryonic development in vitro. However, the effect of ITS both in IVM and IVC media on porcine embryo production in vitro hasn’t been elucidated. In this study, we found that 1.0% ITS supplementation in IVM/IVC media promoted the expansion of cumulus cells, raised mitochondrial membrane potential, increased ATP content and reduced ROS level in matured oocytes, improved blastocyst rate and the cell number of blastocyst, simultaneously. In conclusion, the IVM/IVC media supplemented with 1.0% ITS can improve the efficiency of porcine embryo production in vitro.

The secondary metabolites of several plant species, particularly sesquiterpenic lactones (SLs) have been studied by different research groups for over 30 years. This group of metabolites presents numerous biological activities such as antibacterial, antiviral, antiulcer, cell proliferation inhibitor, and oocyte activator with participation in exocytosis processes. This study aims to assess some sperm parameters in epididymal gametes of Chichilla lanigera exposed to increasing concentrations (0 to 2 mM) of DhL for various incubation times from 10 to 40 minutes. We determined the participation of different cell signalling pathways in the induced acrosome reaction. Our results showed an alteration in the progressive motility pattern and cell viability depending on DhL concentration and exposure time of gametes. When analyzing acrosomal status, higher percentages than the negative control were obtained in all tested doses. Both isolated and joint inhibition tests of PKA and phospholipases (PLC and PLA2) showed a greater participation of PI-PLC. This is the first report concerning the effects of this lactone on the medium of sperm incubation. Consequently, further studies will be necessary to determine the molecular implications of this lactone on the fertilizing potential of the sperm.

EXOSC10 is an exosome-associated ribonuclease that degrades and processes a wide range of transcripts in the nucleus. The initial segment (IS) of the epididymis is crucial for sperm transport and maturation in mice by affecting the absorption and secretion that is required for male fertility. However, the role of EXOSC10 ribonuclease-mediated RNA metabolism within the IS in the regulation of gene expression and sperm maturation remains unknown. Herein, we established an Exosc10 conditional knockout (Exosc10 cKO) mouse model by crossing Exosc10F/F mice with Lcn9-Cre mice which expressed recombinase in the principal cells of IS as early as post-natal day 17. Morphological and histological analyses revealed that Exosc10 cKO males had normal spermatogenesis and development of IS. Moreover, the sperm concentration, morphology, motility, and frequency of acrosome reactions in the cauda epididymides of Exosc10 cKO mice were comparable with those of control mice. Thus, Exosc10 cKO males had normal fertility. Collectively, our genetic mouse model and findings demonstrate that loss of EXOSC10 in the IS of epididymis is dispensable for sperm maturation and male fertility.

Human oocyte maturation is a lengthy process that takes place over the course of which oocytes gain the inherent ability to support the next developmental stages in a progressive manner. This process includes intricate and distinct events related to nuclear and cytoplasmic maturation. Nuclear maturation includes mostly chromosome segregation, whereas rearrangement of organelles, storage of mRNAs and transcription factors occur during cytoplasmic maturation.

Human oocyte maturation, both in vivo and in vitro, occurs through a process that is not yet fully understood. However, it is believed that the second messenger, cyclic adenosine monophosphate (cAMP), plays a pivotal role in the upkeep of the meiotic blocking of the human oocyte. Relatively high levels of cAMP in the human oocyte are required to maintain meiosis blocked, whereas lower levels of cAMP in the oocyte enable meiosis to resume. Oocyte cAMP concentration is controlled by a balance between adenylate cyclase and phosphodiesterases, the enzymes responsible for cAMP generation and breakdown.

In addition to nuclear maturation, the female gamete requires a number of complicated structural and biochemical modifications in the cytoplasmic compartment to be able to fertilize normally. According to ultrastructural studies, during the transition from the germinal vesicle stage to metaphase II (MII), several organelles reorganize their positions. The cytoskeletal microfilaments and microtubules found in the cytoplasm facilitate these movements and regulate chromosomal segregation.

The aim of this review is to focus on the nuclear and cytoplasmic maturation by investigating the changes that take place in the process of oocytes being competent for development.

Growth differentiation factor 9 (GDF9) is an oocyte-specific paracrine factor involved in bidirectional communication, which plays an important role in oocyte developmental competence. In spite of its vital role in reproduction, there is insufficient information about exact transcriptional control mechanism of GDF9. Hence, present study was undertaken with the aim to study the expression of basic helix-loop-helix (bHLH) transcription factors (TFs) such as the factor in the germline alpha (FIGLA), twist-related protein 1 (TWIST1) and upstream stimulating factor 1 and 2 (USF1 and USF2), and nuclear receptor (NR) superfamily TFs like germ cell nuclear factor (GCNF) and oestrogen receptor 2 (ESR2) under three different in vitro maturation (IVM) groups [follicle-stimulating hormone (FSH), insulin-like growth factor-1 (IGF1) and oestradiol)] along with all supplementation group as positive control, to understand their role in regulation of GDF9 expression. Buffalo cumulus–oocyte complexes were aspirated from abattoir-derived ovaries and matured in different IVM groups. Following maturation, TFs expression was studied at 8 h of maturation in all four different IVM groups and correlated with GDF9 expression. USF1 displayed positive whereas GCNF, TWIST1 and ESR2 revealed negative correlation with GDF9 expression. TWIST1 & ESR2 revealing negative correlation with GDF9 expression were found to be positively correlated amongst themselves also. GCNF & USF1 revealing highly significant correlation with GDF9 expression in an opposite manner were found to be negatively correlated. The present study concludes that the expression of GDF9 in buffalo oocytes remains under control through the involvement of NR and bHLH TFs.

Substance use refers to the consumption of drugs that have varying degrees of impact on a persons’ physical, mental and emotional well-being. While the adverse health effects of drugs have been extensively documented, further research is needed to understand their impact on fertility. Studies have indicated that substance use affects both the male and female reproductive systems. As substance use is more prevalent among young adults compared with the elderly, it appears that individuals of reproductive age are particularly vulnerable to the reproductive impairments associated with substance use. Although numerous studies have reported detrimental effects of substance use on pregnant women and their foetus during the post-implantation stages, there are limited studies on critical pre-implantation period and gamete stages. In this narrative review, we aimed to focus on the most significant evidence regarding the impact of substances on gametes and pre-implantation embryos.

Zygote wishes to inform its readers that its Editor-in-Chief has decided to retract the above article after an investigation carried out in compliance with the Committee on Publication Ethics guidelines found that the authors duplicated substantial parts of the following two articles:

1. 1. Kim H, Yamanouchi K, Nishihara M. (2006) Expression of ski in the granulosa cells of atretic follicles in the rat ovary. J. Reprod. Dev. 52, 715–721

2. 2. Kim H, Yamanouchi K, Matsuwaki T, Nishihara M. (2012) Induction of Ski protein expression upon luteinization in rat granulosa cells without a change in its mRNA expression. J. Reprod. Dev. 58, 254–259

Sloan-Kettering virus gene, a product of a cellular proto-oncogene c-Ski is a unique nuclear pro-oncoprotein and belongs to the Ski/Sno proto-oncogene family. The aim of the present study was to locate Ski protein in rat ovaries in order to find insights into the possible involvement of Ski in follicular development. First, expression of c-Ski mRNA in the ovaries of adult female rats was confirmed by RT-PCR. Then, ovaries obtained on the day of estrus were subjected to immunohistochemical analysis for Ski and proliferating cell nuclear antigen (PCNA) in combination with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). RT-PCR and in situ hybridization revealed that c-Ski mRNA was expressed in the ovaries of the adult rat on the day of estrous and localized mainly in the granulose cells. Ski was expressed in granulosa cells that were positive for TUNEL, but negative for PCNA, regardless of the shape and size of follicles. Expression of Ski in TUNEL-positive granulosa cells, but not in PCNA-positive granulosa cells, was also verified in rats having atretic follicles with double staining. These results indicate that Ski is profoundly expressed in the granulosa cells of atretic follicles, but not in growing follicles. Based on the present findings, Ski may play a role in the apoptosis of granulosa cells during follicular atresia.