Gene expression profiles of Japanese precious coral Corallium japonicum during gametogenesis.

Background: Corallium japonicum, a prized resource in Japan, plays a vital role in traditional arts and fishing industries. Because of diminished stock due to overexploitation, ongoing efforts are focused on restoration through transplantation. This study aimed to enhance our understanding of the reproductive biology of these valuable corals and find more efficient methods for sex determination, which may significantly contribute to conservation initiatives. Methods: We used 12 three-month aquarium reared C. japonicum colony fragments, conducted histological analysis for maturity and sex verification, and performed transcriptome analysis via de novo assembly and mapping using the C. rubrum transcriptome to explore gene expression differences between female and male C. japonicum. Results: Our histological observations enabled sex identification in 33% of incompletely mature samples. However, the sex of the remaining 67% of samples, classified as immature, could not be identified. RNA-seq yielded approximately 21-31 million short reads from 12 samples. De novo assembly yielded 404,439 highly expressed transcripts. Among them, 855 showed significant differential expression, with 786 differentially expressed transcripts between females and males. Heatmap analysis highlighted 283 female-specific and 525 male-specific upregulated transcripts. Transcriptome assembly mapped to C. rubrum yielded 28,092 contigs, leading to the identification of 190 highly differentially expressed genes, with 113 upregulated exclusively in females and 70 upregulated exclusively in males. Blastp analysis provided putative protein annotations for 83 female and 72 male transcripts. Annotation analysis revealed that female biological processes were related to oocyte proliferation and reproduction, whereas those in males were associated with cell adhesion. Discussion: Transcriptome analysis revealed sex-specific gene upregulation in incompletely mature C. japonicum and shared transcripts with C. rubrum, providing insight into its gene expression patterns. This study highlights the importance of using both de novo and reference-based assembly methods. Functional enrichment analysis showed that females exhibited enrichment in cell proliferation and reproduction pathways, while males exhibited enrichment in cell adhesion pathways. To the best of our knowledge, this is the first report on the gene expressions of each sex during the spawning season. Our findings offer valuable insights into the physiological ecology of incompletely mature red Japanese precious corals and suggest a method for identifying sex using various genes expressed in female and male individuals. In the future, techniques such as transplantation, artificial fertilization, and larval rearing may involve sex determination methods based on differences in gene expression to help conserve precious coral resources and ecosystems.

Comparative analysis of reproductive tract microbiomes in modern and slower-growing broiler breeder lines.

Introduction: The reproductive tract microbiome in hens is of interest because bacteria in the reproductive tract could potentially affect fertilization and egg production, as well as integrate into the forming egg and vertically transmit to progeny. Methods: The reproductive tract microbiome of 37-week-old modern commercial Cobb breeding dams was compared with that of dams from a broiler Legacy line which has not undergone selection since 1986. All animals were kept together under the same management protocol from day of hatch to avoid confounders. Results: In regards to reproductive abilities, Cobb dams' eggs weighed more and the magnum section of their reproductive tract was longer. In regards to microbiome composition, it was found that the reproductive tract microbiomes of the two lines had a lot in common but also that the two breeds have unique reproductive tract microbiomes. Specifically, the order Pseudomonadales was higher in the magnum of Legacy dams, while Verrucomicrobiales was lower. In the infundibulum, Lactobacillales were higher in the Legacy dams while Verrucomicrobiales, Bacteroidales, RF32 and YS2 were lower. Discussion: our results show that breeding programs have modified not only the physiology of the reproductive tract but also the reproductive tract microbiome. Additional research is required to understand the implications of these changes in the reproductive tract microbiome on the chicken host.

Bubbling beyond the barrier: exosomal RNA as a vehicle for soma-germline communication.

'Weismann's barrier' has restricted theories of heredity to the transmission of genomic variation for the better part of a century. However, the discovery and elucidation of epigenetic mechanisms of gene regulation such as DNA methylation and histone modifications has renewed interest in studies on the inheritance of acquired traits and given them mechanistic plausibility. Although it is now clear that these mechanisms allow many environmentally acquired traits to be transmitted to the offspring, how phenotypic information is communicated from the body to its gametes has remained a mystery. Here, we discuss recent evidence that such communication is mediated by somatic RNAs that travel inside extracellular vesicles to the gametes where they reprogram the offspring epigenome and phenotype. How gametes learn about bodily changes has implications not only for the clinic, but also for evolutionary theory by bringing together intra- and intergenerational mechanisms of phenotypic plasticity and adaptation.

Role of Melatonin in Bovine Reproductive Biotechnology.

Melatonin has profound antioxidant activity and numerous functions in humans as well as in livestock and poultry. Additionally, melatonin plays an important role in regulating the biological rhythms of animals. Combining melatonin with scientific breeding management has considerable potential for optimizing animal physiological functions, but this idea still faces significant challenges. In this review, we summarized the beneficial effects of melatonin supplementation on physiology and reproductive processes in cattle, including granulosa cells, oocytes, circadian rhythm, stress, inflammation, testicular function, spermatogenesis, and semen cryopreservation. There is much emerging evidence that melatonin can profoundly affect cattle. In the future, we hope that melatonin can not only be applied to cattle, but can also be used to safely and effectively improve the efficiency of animal husbandry.

A neuroscience-based approach to the assessment of sexual behavior in animals.

Sexual behavior in animals is important in ensuring the continuity of the generation. These behaviors differ in animal species. Sexual behaviors are shaped under the control of the reproductive system. Physiological stimuli produced by the reproductive system find their counterparts in the organism as reproductive activity. Reproductive activity display a critical role by transferring on the genetic heritage of organisms to the next generations. This activity, which is built on delicate balances, is associated with many systems in the organism. Nervous system, hormonal system, and circulatory system are the main ones. The regular formation of the reproductive activity in species is due to the effect of various factors. In domestic mammals, the reproductive activity is regulated by hormones secreted from brain and endocrine glands. Many hormones have duties in terms of the sustainability of reproductive activity. GnRH is the main hormone responsible for initiating this reproductive activity. Gonadotropin-releasing hormone (GnRH), which is a small molecule peptide from certain nerve cells in the nucleus infundibularis region of the hypothalamus and consists of different amino acids, is secreted under the influence of smell, temperature, light, and physical stimulation. Besides, GnRH release is controlled by various neurotransmitters (adrenaline, noradrenaline, dopamine, acetylcholine, serotonin). On the other hand, various genetic factors in secretory glands, gonadal cells, reproductive tissues can lead to significant changes on reproductive activity through specific molecular pathways and mechanisms.

Sperm can't take the heat: Short-term temperature exposures compromise fertility of male bumble bees (Bombus impatiens).

Bumble bee (genus Bombus) populations are increasingly under threat from habitat fragmentation, pesticides, pathogens, and climate change. Climate change is likely a prime driver of bumble bee declines but the mechanisms by which changing climates alter local abundance, leading to shifts in geographic range are unclear. Heat tolerance is quite high in worker bumble bees (CTmax âˆ¼ 48-55 °C), making it unlikely for them to experience these high temperatures, even with climate warming. However, the thermal tolerance of whole organisms often exceeds that of their gametes; many insects can be sterilized by exposure to temperatures well below their upper thermal tolerance. Male bumble bees are independent from the colony and may encounter more frequent temperature extremes, but whether these exposures compromise spermatozoa is still unclear. Using commercially-reared Bombus impatiens colonies, males were reared in the lab and spermatozoa were exposed (in vivo and isolated in vitro) to sublethal temperatures near lower and upper thermal tolerance (CTmin and CTmax, respectively). Heat exposure (45 °C for up to 85 min) reduced spermatozoa viability both for whole males (in vivo; control = 79.5 %, heat exposed = 58 %, heat stupor = 57.7 %) and isolated seminal vesicles (in vitro; control = 85.5 %, heat exposed = 62.9 %). Whole males exposed to 4 °C for 85 min (in vivo; control = 79.2 %, cold = 72.4 %), isolated seminal vesicles exposed to 4 °C for 85 min (in vitro; control = 85.5 %, cold = 85.1 %), and whole males exposed to for 4 °C for 48 h (in vivo; control = 88.7 %, cold = 84.3 %) did not differ significantly in spermatozoa viability. After<85 min at 45 °C, males had significantly reduced spermatozoa viability, suggesting that short-term heat waves below CTmax could strongly reduce the fertility of male bumble bees with potential population-level impacts.

Melatonin in Reproductive Medicine: A Promising Therapeutic Target?

Melatonin, mainly released from the pineal gland, also produced in the reproductive organs and cells, plays important roles in rhythms of the sleep-wake cycle, retardation of ageing processes, and antioxidant/anti-inflammatory functions. As a key mediator in reproductive systems, melatonin is participated in the reproductive process via regulating gamete and embryo development and influences reproductive diseases and pregnancy outcomes. The underlying mechanisms include epigenetic and other regulations, which are interesting for exploring new targets in the prevention and treatment of reproductive diseases. This review discusses the relationship between melatonin and reproductive functions and dysfunction, as well as potential clinical applications of melatonin in reproductive medicine. Notably, Developmental Origins of Health and Diseases (DOHaD) is closely linked to reproduction, this article is the first to review the new progress in studies on the possible relationship between melatonin and DOHaD.

Oestradiol reduces female bill colour in a mutually ornamented bird.

Carotenoid-based colour signals can be costly to produce and maintain, and trade-offs between signalling and other fitness traits are expected. In mutually ornamented species, trade-offs with reproduction may be stronger for females than males, because females often dedicate more resources to offspring production, which may lead to plastic investment in colour signals and plastic sexual dichromatism. Oestradiol is a candidate mediator of this trade-off because it regulates reproductive physiology and may also influence the expression of coloration. We tested this hypothesis by giving female common waxbills (Estrilda astrild) either oestradiol (17ß-oestradiol) or empty implants during the early breeding season and measured spectral reflectance of carotenoid-based bill coloration weekly for two months. Using a model of avian vision, we found that bill colour in oestradiol-implanted females became less saturated, less red in hue and brighter, compared with control females and with unimplanted males. This resulted in a change in bill sexual dichromatism from imperceptible to perceptible. Results support the hypothesis that female reproductive physiology influences investment in coloration through changes in oestradiol and show a form of female-driven plastic sexual dichromatism. Greater sensitivity of female colour to physiological and/or environmental conditions helps explain why differences in sexual dichromatism among species differing in ecology often evolve owing to changes in female rather than male phenotype.

Reproduction in South American wild canids-A review.

Canids occupy the top of the food chain and are fundamental in sustaining a wild animal/environmental balance. South America, the most biodiverse continent, has 11 species of canids inhabiting diverse biomes, with or without overlapping territories. Although several species are threatened, little is known about their reproductive biology. Remarkably, basic knowledge regarding ejaculate characteristics, sexual behavior, female reproductive cycles, pregnancy and management, and parturition are scarce or absent. These gaps complicate or preclude development of conservation programs. This review compiles the current knowledge of the reproductive biology of South American canids and discusses implications of this scenario.

A Transient Mystery: Nucleolar Channel Systems.

The nucleus is a complex organelle with functions beyond being a simple repository for genomic material. For example, its actions in biomechanical sensing, protein synthesis, and epigenomic regulation showcase how the nucleus integrates multiple signaling modalities to intricately regulate gene expression. This innate dynamism is underscored by subnuclear components that facilitate these roles, with elements of the nucleoskeleton, phase-separated nuclear bodies, and chromatin safeguarding by nuclear envelope proteins providing examples of this functional diversity. Among these, one of the lesser characterized nuclear organelles is the nucleolar channel system (NCS), first reported several decades ago in human endometrial biopsies. This tubular structure, believed to be derived from the inner nuclear membrane of the nuclear envelope, was first observed in secretory endometrial cells during a specific phase of the menstrual cycle. Reported as a consistent, yet transient, nuclear organelle, current interpretations of existing data suggest that it serves as a marker of a window for optimal implantation. In spite of this available data, the NCS remains incompletely characterized structurally and functionally, due in part to its transient spatial and temporal expression. As a further complication, evidence exists showing NCS expression in fetal tissue, suggesting that it may not act exclusively as a marker of uterine receptivity, but rather as a hormone sensor sensitive to estrogen and progesterone ratios. To gain a better understanding of the NCS, current technologies can be applied to profile rare cell populations or capture transient structural dynamics, for example, at a level of sensitivity and resolution not previously possible. Moving forward, advanced characterization of the NCS will shed light on an uncharacterized aspect of reproductive physiology, with the potential to refine assisted reproductive techniques.

Dynamics of the Reproductive Changes and Acquisition of Oocyte Competence in Nelore (Bos taurus indicus) Calves during the Early and Intermediate Prepubertal Periods

The purpose of this study was to characterize the reproductive physiology, oocyte competence, and chromatin compaction in Nelore calves in the early-prepubertal period (EPP) and the intermediate-prepubertal period (IPP). Calves aged 2-5 (EPP) and 8-11 months old (IPP) were assigned to Trial 1 (morpho-physiological-endocrine evaluations, n = 8) or Trial 2 (oocyte donors, n = 8) vs. the respective control groups of cows (n = 8, each). All morphological endpoints, except the antral follicle count, increased from the EPP to the IPP. The EPP LH-FSH plasma concentrations were similar to cows, whereas LH was lower and FSH was higher in the IPP than in cows. . Cows produced more Grade I (12.9% vs. 4.1% and 1.7%) and fewer Grade III COC (30.1% vs. 44.5% and 49.0%) than the EPP and IPP calves, respectively. The IPP calves' oocyte diameter was similar to those from cows but greater than those from EPP females (124.8 ± 8.5 and 126.0 ± 7.5 µm vs. 121.3 ± 7.5 µm, respectively). The expression of the chromatin compaction-related gene HDAC3 was downregulated in calves. The proportion of the blastocyst rate to the controls was lower in EPP than in IPP calves (43.7% vs. 78.7%, respectively). Progressive oocyte competence was found during the prepubertal period, which can help to decide whether to recover oocytes from calves.

Dancing to a different tune: changing reproductive seasonality in an introduced chital deer population.

Male and female reproductive behaviour is typically synchronised. In species such as those in the family Cervidae, reproductive timing is often cued by photoperiod, although in females, it can be dependent on body condition. When a species is introduced to a novel environment, the environment changes, or responses of the sexes to such cues differ, asynchronous reproductive behaviour between males and females may occur. We investigated the seasonality of reproductive behaviour in introduced chital deer in northern Queensland by examining male antler phase in relation to female conception rates. We then analysed the influence of different variables likely to affect the timing of male and female reproductive physiology. The lowest percentage of chital in hard antler in any 1 month in this study was 35% (Fig. 1), but the average value was closer to 50%, thus there was a seasonal peak in antler phase linked with photoperiod. Females conceived at any time of year, but were strongly influenced by the amount of rainfall 3 months prior to conception. This resulted in varying conception peaks year-to-year that often did not correspond to the male's peak in hard antler. In this system, a proportion of males and females were physiologically and behaviourally ready to mate at any time of the year. We predict that differences in the timing of the peaks between the males and females will lead to increased reproductive skew (variation in reproductive success among individual males). This pattern may select for different mating strategies or physiological mechanisms to increase reproductive success. Fig. 1 The average percentage of male chital deer in hard antler by month from 2014 to 2019 in north Queensland. Values above the bars indicate the total number of males that were sampled in each month and the error bars indicate the standard error. In the month with the lowest % males in hard antler in the entire study (November, 2017), 35% of males were in hard antler.

Molecular Cloning and Expression Analysis of Thyrotropin-Releasing Hormone, and Its Possible Role in Gonadal Differentiation in Rice Field eel Monopterus albus.

Rice field eel (Monopterus albus), a protogynous hermaphrodite fish, is a good model for the research of sex determination and gonadal differentiation in teleosts. In this study, we cloned the full-length cDNA sequence of trh, which encoded a predicted protein with 270 amino acids. Trh mainly expressed in the brain, followed by the ovary, testis, muscle and pituitary, and had low levels in other peripheral tissues. During natural sex reversal, trh mRNA expression levels exhibited a significant increase at the late intersexual stage in the hypothalamus. In the gonad, trh mRNA expression levels showed a trend of increase followed by decrease, and only increased significantly at the middle intersexual stage. No matter static incubation or intraperitoneal (IP) injection, TRH had no significant effect on trh and thyroid-stimulating hormone ßsubunit (tshß) mRNA expression levels, and serum T3, T4 and TRH release. After static incubation of ovarian fragments by TRH, the expression of gonadal soma derived factor (gsdf) was up-regulated significantly at both the doses of 10 and 100 nM. IP injection of TRH stimulated the expression of gsdf, and inhibited the expression of ovarian aromatase gene (cyp19a1a), accompanied by the increase of serum 11-KT levels. The results indicated that TRH may play a novel role in gonadal differentiation by the regulation of gonadal differentiation-related gene expression and sex steroid hormone secretion in rice field eel.

The pheromone affects reproductive physiology and behavior by regulating hormone in juvenile mice.

Pheromones could promote hormone secretions and regulate sexual behavior. It was unclear whether multiparous pheromone could induce variations in puberty. The aim was to ascertain whether pheromone in urine of multiparous females induced central precocious puberty (CPP) in juvenile C57BL/6J females. The precocious puberty was examined by vaginal smear, lordosis reaction, HE stain, and ELISA analysis. Results suggested that the first vaginal opening and the first estrus were significantly earlier. The time interval of the first vaginal opening and estrus was significantly shortened. It was interesting that the first estrus was significantly correlated with the first vaginal opening and the time interval of the first estrus. In the first estrus, female lordosis reaction, the number of mature follicles, and the weight of the ovary and uterus significantly increased. The level of luteinizing hormones also significantly increased. Thus, multiparous pheromone can regulate sex hormone to induce CPP in juvenile C57BL/6J females.

Histological Changes in Ovary Treated with Dexamethasone and Cefotaxime Sodium.

Dexamethasone (DEX), which is a corticosteroid hormone (glucocorticoid), has been used to treat different conditions, such as immune system disorders, certain skin and eye disorders, as well as breathing problems. Cefotaxime sodium, also called Claforan, is synthesized from a naturally occurring material (semisynthetic). It is a broad-spectrum cephalosporin antibiotic that could be utilized for parenteral administration. The present study aimed to investigate histological changes occurring in the tissues and cells of the rats' ovary (primordial, primary, secondary, antral, and mature follicle) treated with Cefotaxime sodium, as well as DEX, and evaluate the impacts of these medications on animals' fertility. In total, 40 female adult Wistar rats were divided into four groups (n=10). The control group received 0.5 ml/kg of distilled water daily for five days as a placebo. The second group was injected with 0.5 mg/kg of DEX daily for five days. The same amount of Claforan (0.5 mg/kg) was injected into the third group daily for five days, and the fourth group received 0.5 mg/kg of both Claforan and DEX daily for five days. Afterward, the ovaries were prepared for histological examination. The ImageJ image analysis system was used to detect morphometric parameters and calculate the area of these organs. The findings of the present study showed that the DEX and Claforan brought changes to the ovarian area and the number of follicles. The ovarian area significantly increased (P<0.007) in the DEX-treated group (mean±SEM=7.3±0.5 mm2), compared to the control group (mean±SEM=4.6±0.20 mm2). However, DEX was found to decrease body weight. Furthermore, the ovarian area significantly increased in the Claforan-treated group (mean±SEM=8.6±0.6 mm2); however, their body weight significantly decreased (P<0.008), in comparison with the control and DEX-treated groups. The combination treatment (i.e., DEX + Cefotaxime sodium) significantly increased (P<0.009) the area of ovaries even more, compared to single treatments (mean±SEM=9.6±0.4 mm2). Overall, both DEX and Claforan brought histological changes to ovaries. However, the effect of DEX on ovaries was less than that of Claforan. The concurrent administration of both medications was found to have more significant effects on rats' ovaries.

Transcriptomic Profile of New Gene Markers Encoding Proteins Responsible for Structure of Porcine Ovarian Granulosa Cells.

The extracellular matrix (ECM) in granulosa cells is functionally very important, and it is involved in many processes related to ovarian follicle growth and ovulation. The aim of this study was to describe the expression profile of genes within granulosa cells that are associated with extracellular matrix formation, intercellular signaling, and cell-cell fusion. The material for this study was ovaries of sexually mature pigs obtained from a commercial slaughterhouse. Laboratory-derived granulosa cells (GCs) from ovarian follicles were cultured in a primary in vitro culture model. The extracted genetic material (0, 48, 96, and 144 h) were subjected to microarray expression analysis. Among 81 genes, 66 showed increased expression and only 15 showed decreased expression were assigned to 7 gene ontology groups "extracellular matrix binding", "extracellular matrix structural constituent", "binding, bridging", "cadherin binding", "cell adhesion molecule binding", "collagen binding" and "cadherin binding involved in cell-cell adhesion". The 10 genes with the highest expression (POSTN, ITGA2, FN1, LAMB1, ITGB3, CHI3L1, PCOLCE2, CAV1, DCN, COL14A1) and 10 of the most down-regulated (SPP1, IRS1, CNTLN, TMPO, PAICS, ANK2, ADAM23, ABI3BP, DNAJB1, IGF1) were selected for further analysis. The results were validated by RT-qPCR. The current results may serve as preliminary data for further analyses using in vitro granulosa cell cultures in assisted reproduction technologies, studies of pathological processes in the ovary as well as in the use of the stemness potential of GCs.

Expression of reproductive-related genes and changes in oocyte maturation of goldfish broodstock (Carassius auratus) following injection of different exogenous kisspeptins.

Kisspeptin, upstream of the hypothalamic-pituitary-gonadal axis, play an essential role in the reproductive process. In the present study, the effect of different types of kisspeptin, including goldfish (Carassius auratus) kiss1 kisspeptin (Kiss1), human kisspeptin (Hkiss) and their combination (Kiss1+H) on the reproductive-related genes (kiss1, Kissr and Cyp19) of adult female goldfish was investigated in comparison with Ovaprim (a synthetic GnRH hormone). Kiss1 and Hkiss were synthesized using a solid-phase synthesis approach. Peptides were injected at a dose of 100 µg/kg body weight. The brain and ovarian tissues of samples were separated for histological studies 24 hr post-injection. The expression of the kiss1, Kissr and Cyp19 genes was measured by RT-PCR. The results showed a significant increase in expression of the reproductive-related genes. Histological analysis revealed higher number of mature oocytes in kisspeptin treated groups compare to other ones. In conclusion, Hkiss and Kiss1+H are the most effective peptides in oocyte maturation and expression of reproductive-related genes. In addition, it seems that kisspeptins in other domestic animals can be used to stimulate the hypothalamus-pituitary-gonadal axis.

Analysis of correlated responses in key ejaculatory traits to artificial selection on a diversifying secondary sexual trait.

Positive genetic covariance between male sexual display traits and fertilizing capacity can arise through different mechanisms and has important implications for sexual trait evolution. Evidence for such genetic covariance is rare, and when it has been found, specific physiological traits underlying variation in fertilization success linked to trait expression have not been identified. A previous study of correlated responses to bidirectional artificial selection on the male sex comb, a secondary sexual trait, in Drosophila bipectinata Duda documented a positive genetic correlation between sexual trait size and competitive fertilization success, and found that transcript levels of multiple seminal fluid proteins (SFPs) were significantly increased in the large sex comb (high) genetic lines. These results suggest that changes in SFP activity may be a causal factor underlying the increased fertilizing capacity of high line males. Here, we tested for correlated responses to this selection in a suite of additional reproductive traits, measured in the context of variation in male age and exposure to rivals. Whereas several traits including sperm length, number and viability, and accessory gland size, increased with age, only sperm viability was influenced by selection treatment, but in complex fashion. Sperm viability of high line males surpassed that of their smaller-combed counterparts when they had been housed with rivals and were 5-6 days old or older. Interestingly, this interaction effect was evident for sperm sampled from the female seminal receptacle, but not from the male seminal vesicles (where sperm have yet to be combined with accessory gland products), consistent with the differential SFP activity between the lines previously found. Our results suggest that differences in sperm quality (as viability) may be a contributing factor to the positive genetic correlation between sexual trait size and competitive fertilization capacity in D. bipectinata.

Testicular Melatonin and Its Pathway in Roe Deer Bucks (Capreolus capreolus) during Pre- and Post-Rut Periods: Correlation with Testicular Involution.

Roe deer are seasonal breeders with a complete yearly testicular cycle. The peak in reproductive activity is recorded during summer, the rutting period, with the highest levels of androgens and testicular weight. Melatonin plays a pivotal role in seasonal breeders by stimulating the hypothalamus-pituitary-gonads axis and acting locally; in different species, its synthesis within testes has been reported. The aim of this study was to evaluate the physiological melatonin pattern within roe deer testes by comparing data obtained from animals sampled during pre- and post-rut periods. Melatonin was quantified in testicular parenchyma, along with the genetic expression of enzymes involved in its local synthesis (AANAT and ASMT) and function (UCP1). Melatonin receptors, MT1-2, were quantified both at protein and gene expression levels. Finally, to assess changes in reproductive hormonal profiles, testicular dehydroepiandrosterone (DHEA) was quantified and used for a correlation analysis. Melatonin and AANAT were detected in all samples, without significant differences between pre- and post-rut periods. Despite DHEA levels confirming testicular involution during the post-rut period, no correlations appeared between such involution and melatonin pathways. This study represents the first report regarding melatonin synthesis in roe deer testes, opening the way for future prospective studies in the physiology of this species.