Melissa Serna - Academia.edu (original) (raw)

Papers by Melissa Serna

Research paper thumbnail of Effect of melatonin on ram sperm capacitation induced by epidermal growth factor

Animal Reproduction Science, Dec 1, 2022

Research paper thumbnail of Influence of melatonin receptor 1A (MTNR1A) gene polymorphisms on melatonin synthetizing-enzymes and melatonin receptors gene expression in ram

Animal Reproduction Science

Research paper thumbnail of Effect of melatonin and nitric oxide on capacitation and apoptotic changes induced by epidermal growth factor in ram sperm

Reproduction, Fertility and Development

Context Apart from the canonical cAMP-PKA pathway, ram sperm capacitation can be achieved by the ... more Context Apart from the canonical cAMP-PKA pathway, ram sperm capacitation can be achieved by the MAPK ERK1/2 signalling cascade, activated by epidermal growth factor (EGF). Aims This study aims to investigate the effect of melatonin and nitric oxide (NO·) on capacitation and apoptotic-like changes in EGF-capacitated ram spermatozoa. Methods In vitro capacitation was induced by EGF in the absence or presence of melatonin (100 pM or 1 μM). Also, a NO· precursor, L-arginine, or a NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), were added to capacitation media to study the interaction of NO· and melatonin during EGF-capacitation. Sperm functionality parameters (motility, viability, capacitation state), apoptotic markers (caspase activation and DNA damage), NO· levels, and phosphorylated c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (assessed by Western blot), were evaluated in swim-up and capacitated samples with EGF. Key results NO· levels and the apo...

Research paper thumbnail of Sperm Behavior and Response to Melatonin under Capacitating Conditions in Three Sheep Breeds Subject to the Equatorial Photoperiod

Animals

In this study, we demonstrated that, in seasonal Mediterranean ovine breeds, supplementing the TA... more In this study, we demonstrated that, in seasonal Mediterranean ovine breeds, supplementing the TALP medium with cAMP-elevating agents (the cocktail medium) is effective for achieving ram sperm capacitation, and that melatonin is able to regulate this phenomenon. We investigated the behavior under capacitating conditions using the TALP and cocktail mediums, and the response to melatonin, of spermatozoa from three sheep breeds (Colombian Creole, Romney Marsh, and Hampshire) subject to the equatorial photoperiod, during the dry and the rainy seasons. The cocktail medium was able to induce sperm capacitation, assayed by chlortetracycline staining and phosphotyrosine levels, to a greater extent than TALP, without a higher loss of viability (membrane integrity and viable spermatozoa without phosphatidylserine (PS) translocation). The addition of melatonin at 100 pM or 1 µM in the cocktail medium partially prevented the decrease in viability without PS translocation and the increase in cap...

Research paper thumbnail of Datasheet Biology_ecography

Data obtained for the MDPI <br>

Research paper thumbnail of Effect of adding antioxidants in diluents for the preservation of sheep semen

Revista de Medicina Veterinaria, 2019

Research paper thumbnail of Effect of environmental factors on ram sperm quality under tropical conditions

Research paper thumbnail of Testicular Ultrasound Analysis as a Predictive Tool of Ram Sperm Quality

Biology, 2022

Testicular ultrasound is a non-invasive technique that could be very useful for predicting ram se... more Testicular ultrasound is a non-invasive technique that could be very useful for predicting ram seminal quality. Recent software developments allow macroscopic and microscopic evaluation of testicular parenchyma. Thus, the aim of this study was to evaluate the testicular echotexture using ultrasound-video analysis and investigate its possible correlation with semen quality. Nine rams were evaluated for one year using a portable ultrasound scanner and the echotexture was analyzed with ECOTEXT® software. The number of black (Ec1), white (Ec2), and grey pixels (Ec3), tubular density (TD), lumen area (LA), and lumen diameter (LD) were analyzed. Semen was collected by an artificial vagina the same day and the sperm concentration, morphology, motility, viability, phosphatidylserine (PS) translocation, reactive-oxygen-species (ROS) levels, DNA damage and capacitation state were evaluated. Ec2 and Ec3 correlated positively with “bad quality” sperm parameters (the percentage of spermatozoa wi...

Research paper thumbnail of Effect of Body Condition Score, Treatment Period and Month of the Previous Lambing on the Reproductive Resumption of Melatonin-Treated Sarda Breed Sheep during Spring

Animals, 2021

Stakeholders place great emphasis upon rationalizing the management and rearing techniques which ... more Stakeholders place great emphasis upon rationalizing the management and rearing techniques which are utilized within sheep farms. The present study aimed to investigate factors which may improve the reproductive performance of melatonin-treated Sardinian sheep via a series of three trials. The first trial (n = 100) investigated the effect of melatonin treatment alongside body condition score (BCS), the second trial (n = 150) investigated the effect of treatment alongside the date of treatment (treatment period) and the third trial (n = 150) investigated the effect of treatment alongside the previous lambing of the ewes. The findings indicated that melatonin is an effective tool for anticipating and improving the reproductive activity of in Sarda breed sheep during the springtime. Furthermore, to obtain optional results, melatonin implantation should be conducted in April, in ewes that have a BCS of >2.5 and that have passed their third month of lactation.

Research paper thumbnail of NADPH Oxidase 5 and Melatonin: Involvement in Ram Sperm Capacitation

Frontiers in Cell and Developmental Biology, 2021

Reactive oxygen species (ROS) play an essential role in mammalian sperm capacitation. NADPH oxida... more Reactive oxygen species (ROS) play an essential role in mammalian sperm capacitation. NADPH oxidase 5 (NOX5) has been described as the main source of ROS production in some mammalian spermatozoa, such as human and equine. On the other hand, melatonin can decrease cellular ROS levels and regulates NOX activity in somatic cells. Therefore, the objectives of this work were (1) to identify NOX5 in ram spermatozoa and analyze its possible changes during in vitro capacitation and (2) to investigate the effect of melatonin on NOX5 expression and localization and on superoxide levels in capacitated ram spermatozoa. Protein bands associated with NOX5 were detected by Western blot analysis. Likewise, indirect immunofluorescence (IIF) revealed six different immunotypes for NOX5, which varied throughout in vitro capacitation. Superoxide (O2⋅–), evaluated by DHE/Yo-Pro-1, rose after in vitro capacitation and in the presence of the calcium ionophore A23187 but decreased in the presence of the NOX...

Research paper thumbnail of Vasectomy and Photoperiodic Regimen Modify the Protein Profile, Hormonal Content and Antioxidant Enzymes Activity of Ram Seminal Plasma

International Journal of Molecular Sciences, 2020

This work aimed to determine the contribution of the testis and epididymis and the effect of the ... more This work aimed to determine the contribution of the testis and epididymis and the effect of the photoperiodic regimen on ram seminal plasma (SP). Semen was collected from 15 mature rams located in an equatorial (Colombian Creole and Romney Marsh, eight intact and two vasectomized) or a temperate climate (Rasa Aragonesa, three intact and two vasectomized). SP proteins were analyzed by Bradford, SDS-PAGE and difference gel electrophoresis (DIGE). Melatonin and testosterone concentrations were quantified by ELISA, and activity of glutathione peroxidase (GPx), glutathione reductase (GRD), and catalase by enzymatic assays. Vasectomy increased protein concentration and the intensity of high molecular weight bands (p < 0.001), with no differences between breeds. DIGE revealed the absence of six proteins in vasectomized rams: angiotensin-converting enzyme, lactotransferrin, phosphoglycerate kinase, sorbitol dehydrogenase, epididymal secretory glutathione peroxidase and epididymal secret...

Research paper thumbnail of Effect of melatonin on actin and α-tubulin distribution related to in vitro capacitation in ram sperm

Animal Reproduction Science, 2020

Research paper thumbnail of Decapacitating effect of melatonin is not mediated by calcium-calmodulin kinase II in ram spermatozoa

Animal Reproduction Science, 2020

Research paper thumbnail of Polymorphisms of the melatonin receptor 1A (MTNR1A) gene influence the age at first mating in autumn-born ram-lambs and sexual activity of adult rams in spring

Theriogenology, 2020

The aim of this study was to determine whether polymorphisms of the melatonin receptor 1A (MTNR1A... more The aim of this study was to determine whether polymorphisms of the melatonin receptor 1A (MTNR1A) gene influence the age at first mating in autumn-born ram-lambs and influence the out-of-season sexual activity of adult rams. In experiment 1, 24 Rasa Aragonesa ram-lambs born in September were genotyped for their RsaI and MnlI allelic variants of the MTNR1A gene, and the date of their first mounting with ejaculation after a period of semen collection training was documented. In experiment 2, the reproductive behavior, testicle size, and plasma testosterone concentrations of 18 adult rams (6 rams for each RsaI genotype) were recorded at the beginning (March) and end (May) of the seasonal anestrus.

Research paper thumbnail of Melatonin membrane receptors MT1 and MT2 are expressed in ram spermatozoa from non-seasonal breeds

Tropical Animal Health and Production, 2020

In mammals, many melatonin biological functions are mediated through its interaction with the mem... more In mammals, many melatonin biological functions are mediated through its interaction with the membrane receptors MT 1 and MT 2. We have previously reported their presence in ram spermatozoa from males located in temperate climates, but there is no information on their presence in spermatozoa from rams in areas with an equatorial photoperiod (12L:12D). Thus, we have investigated the existence and cellular distribution of melatonin receptors in spermatozoa from three sheep breeds in Colombia (Colombian Creole, Hampshire, and Romney Marsh) during dry and rainy seasons, using indirect immunofluorescence and western blot. Our results indicated the presence of melatonin receptors in spermatozoa from these rams, and that their distribution differs from that previously found in spermatozoa from rams in temperate climates. Moreover, two new immunotypes of MT 2 were identified: type N, with staining only in the neck, and type E with a band of immunofluorescence in the upper part of the post-acrosome and the apical edge. Likewise, differences between breeds and climate seasons were detected for both receptors. However, densitometry analysis of western blot bands only revealed differences between seasons in the Creole rams for MT 1 and the Romney Marsh rams for MT 2 , whereas differences between breeds were only detected for MT 2. It could be inferred that melatonin receptors in rams subjected to an equatorial photoperiod might be more closely related to sperm quality than seasonal control. Therefore, the presence of these receptors suggests that melatonin could be a useful tool to increase the fertility of rams located in tropical or equatorial climates.

Research paper thumbnail of Nota técnica: La actividad sexual de corderos a los ocho meses de edad como predictor de su actividad sexual adulta

Informacion Tecnica Economica Agraria, 2020

Predecir la actividad sexual de un morueco lo antes posible puede ser una herramienta de gran uti... more Predecir la actividad sexual de un morueco lo antes posible puede ser una herramienta de gran utilidad, especialmente en centros de selección y recogida de semen. El objetivo de este trabajo fue estudiar la concordancia de la actividad sexual-medida a través de test de comportamiento-de moruecos a los 8 y a los 32 meses de edad, para predecir el comportamiento sexual adulto a una edad temprana. Para ello, se sometió a sendos test de monta en el mes de junio (20 minutos de exposición a tres ovejas en celo) a 18 moruecos nacidos en octubre, a los 8 y 32 meses de edad. Se midieron el número de aproximaciones a las hembras y los intentos de monta con y sin eyaculado de cada animal. Cada macho fue clasificado en un ranking del 1 al 18 (1: mejor macho; 18: peor macho) tras calcularse su calificación (número total de eventos observados). Se aplicó un modelo de regresión lineal para predecir el ranking y la calificación adulta a partir de la juvenil. Ambos parámetros adultos se relacionaron en gran medida con los tempranos (r 2 = 0,594 y 0,365, respectivamente; p < 0,0001). La predicción fue especialmente buena para los peores machos, de modo que los ocho últimos corderos del ranking fueron igualmente los ocho últimos moruecos a los 32 meses. En conclusión, la actividad sexual adulta de un morueco podría predecirse con una alta determinación a partir de su medición a edades tempranas, siendo una herramienta especialmente útil para eliminar precozmente los peores machos.

Research paper thumbnail of The continuous presence of ewes in estrus in spring influences testicular volume, testicular echogenicity and testosterone concentration, but not LH pulsatility in rams

Animal, 2020

The continuous presence of active male small ruminants prevents seasonal anestrus in females, but... more The continuous presence of active male small ruminants prevents seasonal anestrus in females, but evidence of the same mechanism operating from the females to the males is scarce. This study assessed the effects of the continuous presence of ewes in estrus in spring on ram sexual activity, testicular size and echogenicity, and LH and testosterone concentrations. On 1 March, 20 rams were assigned to two groups (n = 10 each): isolated (ISO) from other sheep, or stimulated (STI) by 12 ewes, which were separated from the rams by an openwork metal barrier, allowing contact between sexes. Each week, four ewes were induced into estrus by intravaginal sponges. Live weight, scrotal circumference, testicular width (TW) and length (TL) were recorded at the beginning and at the end of the experiment, and testicular volume (TV) was calculated; at the same time, testicular ultrasonography and color Doppler scanning were performed. Blood samples (March to May) were collected once per week for test...

Research paper thumbnail of Does Melatonin Exert Its Effect on Ram Sperm Capacitation Through Nitric Oxide Synthase Regulation?

International Journal of Molecular Sciences, 2020

Nitric oxide (NO·), synthesized from L-arginine by nitric oxide synthase (NOS), is involved in sp... more Nitric oxide (NO·), synthesized from L-arginine by nitric oxide synthase (NOS), is involved in sperm functionality. NOS isoforms have been detected in spermatozoa from different species, and an increment in NOS activity during capacitation has been reported. This work aims to determine the presence and localization of NOS isoforms in ram spermatozoa and analyse their possible changes during in vitro capacitation. Likewise, we investigated the effect of melatonin on the expression and localization of NOS and NO· levels in capacitated ram spermatozoa. Western blot analysis revealed protein bands associated with neuronal NOS (nNOS) and epithelial NOS (eNOS) but not with inducible NOS (iNOS). However, the three isoforms were detected by indirect immunofluorescence (IFI), and their immunotypes varied over in vitro capacitation with cAMP-elevating agents. NO· levels (evaluated by DAF-2-DA/PI staining) increased after in vitro capacitation, and the presence of L-arginine in the capacitatin...

Research paper thumbnail of Sperm quality and seminal plasma proteins in three sheep breeds under high altitude and tropical conditions

Spanish Journal of Agricultural Research, 2018

We tested the hypothesis that sheep breed can influence the sperm quality and seminal plasma (SP)... more We tested the hypothesis that sheep breed can influence the sperm quality and seminal plasma (SP) composition and investigated any potential relationship between SP proteins and antioxidant enzyme activities (AO) with sperm quality. Ejaculates from twelve rams of three breeds were obtained during the rainy season at high altitudes, and sperm quality was automatically evaluated (CASA-Hamilton Thorne). The AO of superoxide dismutase, glutathione peroxide and glutathione reductase (GR) in SP was evaluated and total proteins were separated by SDS-PAGE. Comparative analyses of semen quality parameters between breeds revealed that Creole and Hampshire breeds had a higher sperm quality compared with Romney Marsh (p<0.05), although no difference in AO was found. GR activity was negatively correlated (p<0.05) with several kinematic variables and positively (p<0.05) with morphological abnormalities. The highest SP protein concentration was found in semen collected from Hampshire male...

Research paper thumbnail of Presence of melatonin‐catabolizing non‐specific enzymes myeloperoxidase and indoleamine 2,3‐dioxygenase in the ram reproductive tract

Reproduction in Domestic Animals, 2019

The melatonin catabolism is very complex and not completely understood. Melatonin can be metaboli... more The melatonin catabolism is very complex and not completely understood. Melatonin can be metabolized by free radical interaction, but also by pseudo-enzymatically or enzymatic pathways. We have previously detected the existence of melatonin-synthesizing enzymes and melatonin receptors MT1 and MT2 in the ram reproductive tract, thus, in order to start to elucidate melatonin catabolism in these organs, we have investigated the presence of the melatonin-catabolizing enzymes indoleamine 2,3-dioxygenase (IDO, both IDO1 and IDO2 isoforms) and myeloperoxidase (MPO) in testis, epididymis and accessory glands. Gene expression analyses by real-time PCR showed the presence of MPO, IDO1, and IDO2 in all the organs of the ram reproductive tract, and revealed that MPO is the main melatonin-catabolizing enzyme, which is mainly expressed in the testis and the bulbourethral glands (P<0.05). These results were further corroborated by immunohistochemical staining, and by western-blot. Likewise, MPO was also evidenced in epididymal and ejaculated spermatozoa by indirect immunofluorescence and western-blot. In conclusion, melatonin catabolizing enzymes MPO, IDO1, and IDO2 are expressed in the ram reproductive tract, and MPO is the most expressed one, mainly in the testis and the bulbourethral glands. The presented results warrant further studies on the function of these enzymes and their melatonin metabolizing activity.

Research paper thumbnail of Effect of melatonin on ram sperm capacitation induced by epidermal growth factor

Animal Reproduction Science, Dec 1, 2022

Research paper thumbnail of Influence of melatonin receptor 1A (MTNR1A) gene polymorphisms on melatonin synthetizing-enzymes and melatonin receptors gene expression in ram

Animal Reproduction Science

Research paper thumbnail of Effect of melatonin and nitric oxide on capacitation and apoptotic changes induced by epidermal growth factor in ram sperm

Reproduction, Fertility and Development

Context Apart from the canonical cAMP-PKA pathway, ram sperm capacitation can be achieved by the ... more Context Apart from the canonical cAMP-PKA pathway, ram sperm capacitation can be achieved by the MAPK ERK1/2 signalling cascade, activated by epidermal growth factor (EGF). Aims This study aims to investigate the effect of melatonin and nitric oxide (NO·) on capacitation and apoptotic-like changes in EGF-capacitated ram spermatozoa. Methods In vitro capacitation was induced by EGF in the absence or presence of melatonin (100 pM or 1 μM). Also, a NO· precursor, L-arginine, or a NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), were added to capacitation media to study the interaction of NO· and melatonin during EGF-capacitation. Sperm functionality parameters (motility, viability, capacitation state), apoptotic markers (caspase activation and DNA damage), NO· levels, and phosphorylated c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (assessed by Western blot), were evaluated in swim-up and capacitated samples with EGF. Key results NO· levels and the apo...

Research paper thumbnail of Sperm Behavior and Response to Melatonin under Capacitating Conditions in Three Sheep Breeds Subject to the Equatorial Photoperiod

Animals

In this study, we demonstrated that, in seasonal Mediterranean ovine breeds, supplementing the TA... more In this study, we demonstrated that, in seasonal Mediterranean ovine breeds, supplementing the TALP medium with cAMP-elevating agents (the cocktail medium) is effective for achieving ram sperm capacitation, and that melatonin is able to regulate this phenomenon. We investigated the behavior under capacitating conditions using the TALP and cocktail mediums, and the response to melatonin, of spermatozoa from three sheep breeds (Colombian Creole, Romney Marsh, and Hampshire) subject to the equatorial photoperiod, during the dry and the rainy seasons. The cocktail medium was able to induce sperm capacitation, assayed by chlortetracycline staining and phosphotyrosine levels, to a greater extent than TALP, without a higher loss of viability (membrane integrity and viable spermatozoa without phosphatidylserine (PS) translocation). The addition of melatonin at 100 pM or 1 µM in the cocktail medium partially prevented the decrease in viability without PS translocation and the increase in cap...

Research paper thumbnail of Datasheet Biology_ecography

Data obtained for the MDPI <br>

Research paper thumbnail of Effect of adding antioxidants in diluents for the preservation of sheep semen

Revista de Medicina Veterinaria, 2019

Research paper thumbnail of Effect of environmental factors on ram sperm quality under tropical conditions

Research paper thumbnail of Testicular Ultrasound Analysis as a Predictive Tool of Ram Sperm Quality

Biology, 2022

Testicular ultrasound is a non-invasive technique that could be very useful for predicting ram se... more Testicular ultrasound is a non-invasive technique that could be very useful for predicting ram seminal quality. Recent software developments allow macroscopic and microscopic evaluation of testicular parenchyma. Thus, the aim of this study was to evaluate the testicular echotexture using ultrasound-video analysis and investigate its possible correlation with semen quality. Nine rams were evaluated for one year using a portable ultrasound scanner and the echotexture was analyzed with ECOTEXT® software. The number of black (Ec1), white (Ec2), and grey pixels (Ec3), tubular density (TD), lumen area (LA), and lumen diameter (LD) were analyzed. Semen was collected by an artificial vagina the same day and the sperm concentration, morphology, motility, viability, phosphatidylserine (PS) translocation, reactive-oxygen-species (ROS) levels, DNA damage and capacitation state were evaluated. Ec2 and Ec3 correlated positively with “bad quality” sperm parameters (the percentage of spermatozoa wi...

Research paper thumbnail of Effect of Body Condition Score, Treatment Period and Month of the Previous Lambing on the Reproductive Resumption of Melatonin-Treated Sarda Breed Sheep during Spring

Animals, 2021

Stakeholders place great emphasis upon rationalizing the management and rearing techniques which ... more Stakeholders place great emphasis upon rationalizing the management and rearing techniques which are utilized within sheep farms. The present study aimed to investigate factors which may improve the reproductive performance of melatonin-treated Sardinian sheep via a series of three trials. The first trial (n = 100) investigated the effect of melatonin treatment alongside body condition score (BCS), the second trial (n = 150) investigated the effect of treatment alongside the date of treatment (treatment period) and the third trial (n = 150) investigated the effect of treatment alongside the previous lambing of the ewes. The findings indicated that melatonin is an effective tool for anticipating and improving the reproductive activity of in Sarda breed sheep during the springtime. Furthermore, to obtain optional results, melatonin implantation should be conducted in April, in ewes that have a BCS of >2.5 and that have passed their third month of lactation.

Research paper thumbnail of NADPH Oxidase 5 and Melatonin: Involvement in Ram Sperm Capacitation

Frontiers in Cell and Developmental Biology, 2021

Reactive oxygen species (ROS) play an essential role in mammalian sperm capacitation. NADPH oxida... more Reactive oxygen species (ROS) play an essential role in mammalian sperm capacitation. NADPH oxidase 5 (NOX5) has been described as the main source of ROS production in some mammalian spermatozoa, such as human and equine. On the other hand, melatonin can decrease cellular ROS levels and regulates NOX activity in somatic cells. Therefore, the objectives of this work were (1) to identify NOX5 in ram spermatozoa and analyze its possible changes during in vitro capacitation and (2) to investigate the effect of melatonin on NOX5 expression and localization and on superoxide levels in capacitated ram spermatozoa. Protein bands associated with NOX5 were detected by Western blot analysis. Likewise, indirect immunofluorescence (IIF) revealed six different immunotypes for NOX5, which varied throughout in vitro capacitation. Superoxide (O2⋅–), evaluated by DHE/Yo-Pro-1, rose after in vitro capacitation and in the presence of the calcium ionophore A23187 but decreased in the presence of the NOX...

Research paper thumbnail of Vasectomy and Photoperiodic Regimen Modify the Protein Profile, Hormonal Content and Antioxidant Enzymes Activity of Ram Seminal Plasma

International Journal of Molecular Sciences, 2020

This work aimed to determine the contribution of the testis and epididymis and the effect of the ... more This work aimed to determine the contribution of the testis and epididymis and the effect of the photoperiodic regimen on ram seminal plasma (SP). Semen was collected from 15 mature rams located in an equatorial (Colombian Creole and Romney Marsh, eight intact and two vasectomized) or a temperate climate (Rasa Aragonesa, three intact and two vasectomized). SP proteins were analyzed by Bradford, SDS-PAGE and difference gel electrophoresis (DIGE). Melatonin and testosterone concentrations were quantified by ELISA, and activity of glutathione peroxidase (GPx), glutathione reductase (GRD), and catalase by enzymatic assays. Vasectomy increased protein concentration and the intensity of high molecular weight bands (p < 0.001), with no differences between breeds. DIGE revealed the absence of six proteins in vasectomized rams: angiotensin-converting enzyme, lactotransferrin, phosphoglycerate kinase, sorbitol dehydrogenase, epididymal secretory glutathione peroxidase and epididymal secret...

Research paper thumbnail of Effect of melatonin on actin and α-tubulin distribution related to in vitro capacitation in ram sperm

Animal Reproduction Science, 2020

Research paper thumbnail of Decapacitating effect of melatonin is not mediated by calcium-calmodulin kinase II in ram spermatozoa

Animal Reproduction Science, 2020

Research paper thumbnail of Polymorphisms of the melatonin receptor 1A (MTNR1A) gene influence the age at first mating in autumn-born ram-lambs and sexual activity of adult rams in spring

Theriogenology, 2020

The aim of this study was to determine whether polymorphisms of the melatonin receptor 1A (MTNR1A... more The aim of this study was to determine whether polymorphisms of the melatonin receptor 1A (MTNR1A) gene influence the age at first mating in autumn-born ram-lambs and influence the out-of-season sexual activity of adult rams. In experiment 1, 24 Rasa Aragonesa ram-lambs born in September were genotyped for their RsaI and MnlI allelic variants of the MTNR1A gene, and the date of their first mounting with ejaculation after a period of semen collection training was documented. In experiment 2, the reproductive behavior, testicle size, and plasma testosterone concentrations of 18 adult rams (6 rams for each RsaI genotype) were recorded at the beginning (March) and end (May) of the seasonal anestrus.

Research paper thumbnail of Melatonin membrane receptors MT1 and MT2 are expressed in ram spermatozoa from non-seasonal breeds

Tropical Animal Health and Production, 2020

In mammals, many melatonin biological functions are mediated through its interaction with the mem... more In mammals, many melatonin biological functions are mediated through its interaction with the membrane receptors MT 1 and MT 2. We have previously reported their presence in ram spermatozoa from males located in temperate climates, but there is no information on their presence in spermatozoa from rams in areas with an equatorial photoperiod (12L:12D). Thus, we have investigated the existence and cellular distribution of melatonin receptors in spermatozoa from three sheep breeds in Colombia (Colombian Creole, Hampshire, and Romney Marsh) during dry and rainy seasons, using indirect immunofluorescence and western blot. Our results indicated the presence of melatonin receptors in spermatozoa from these rams, and that their distribution differs from that previously found in spermatozoa from rams in temperate climates. Moreover, two new immunotypes of MT 2 were identified: type N, with staining only in the neck, and type E with a band of immunofluorescence in the upper part of the post-acrosome and the apical edge. Likewise, differences between breeds and climate seasons were detected for both receptors. However, densitometry analysis of western blot bands only revealed differences between seasons in the Creole rams for MT 1 and the Romney Marsh rams for MT 2 , whereas differences between breeds were only detected for MT 2. It could be inferred that melatonin receptors in rams subjected to an equatorial photoperiod might be more closely related to sperm quality than seasonal control. Therefore, the presence of these receptors suggests that melatonin could be a useful tool to increase the fertility of rams located in tropical or equatorial climates.

Research paper thumbnail of Nota técnica: La actividad sexual de corderos a los ocho meses de edad como predictor de su actividad sexual adulta

Informacion Tecnica Economica Agraria, 2020

Predecir la actividad sexual de un morueco lo antes posible puede ser una herramienta de gran uti... more Predecir la actividad sexual de un morueco lo antes posible puede ser una herramienta de gran utilidad, especialmente en centros de selección y recogida de semen. El objetivo de este trabajo fue estudiar la concordancia de la actividad sexual-medida a través de test de comportamiento-de moruecos a los 8 y a los 32 meses de edad, para predecir el comportamiento sexual adulto a una edad temprana. Para ello, se sometió a sendos test de monta en el mes de junio (20 minutos de exposición a tres ovejas en celo) a 18 moruecos nacidos en octubre, a los 8 y 32 meses de edad. Se midieron el número de aproximaciones a las hembras y los intentos de monta con y sin eyaculado de cada animal. Cada macho fue clasificado en un ranking del 1 al 18 (1: mejor macho; 18: peor macho) tras calcularse su calificación (número total de eventos observados). Se aplicó un modelo de regresión lineal para predecir el ranking y la calificación adulta a partir de la juvenil. Ambos parámetros adultos se relacionaron en gran medida con los tempranos (r 2 = 0,594 y 0,365, respectivamente; p < 0,0001). La predicción fue especialmente buena para los peores machos, de modo que los ocho últimos corderos del ranking fueron igualmente los ocho últimos moruecos a los 32 meses. En conclusión, la actividad sexual adulta de un morueco podría predecirse con una alta determinación a partir de su medición a edades tempranas, siendo una herramienta especialmente útil para eliminar precozmente los peores machos.

Research paper thumbnail of The continuous presence of ewes in estrus in spring influences testicular volume, testicular echogenicity and testosterone concentration, but not LH pulsatility in rams

Animal, 2020

The continuous presence of active male small ruminants prevents seasonal anestrus in females, but... more The continuous presence of active male small ruminants prevents seasonal anestrus in females, but evidence of the same mechanism operating from the females to the males is scarce. This study assessed the effects of the continuous presence of ewes in estrus in spring on ram sexual activity, testicular size and echogenicity, and LH and testosterone concentrations. On 1 March, 20 rams were assigned to two groups (n = 10 each): isolated (ISO) from other sheep, or stimulated (STI) by 12 ewes, which were separated from the rams by an openwork metal barrier, allowing contact between sexes. Each week, four ewes were induced into estrus by intravaginal sponges. Live weight, scrotal circumference, testicular width (TW) and length (TL) were recorded at the beginning and at the end of the experiment, and testicular volume (TV) was calculated; at the same time, testicular ultrasonography and color Doppler scanning were performed. Blood samples (March to May) were collected once per week for test...

Research paper thumbnail of Does Melatonin Exert Its Effect on Ram Sperm Capacitation Through Nitric Oxide Synthase Regulation?

International Journal of Molecular Sciences, 2020

Nitric oxide (NO·), synthesized from L-arginine by nitric oxide synthase (NOS), is involved in sp... more Nitric oxide (NO·), synthesized from L-arginine by nitric oxide synthase (NOS), is involved in sperm functionality. NOS isoforms have been detected in spermatozoa from different species, and an increment in NOS activity during capacitation has been reported. This work aims to determine the presence and localization of NOS isoforms in ram spermatozoa and analyse their possible changes during in vitro capacitation. Likewise, we investigated the effect of melatonin on the expression and localization of NOS and NO· levels in capacitated ram spermatozoa. Western blot analysis revealed protein bands associated with neuronal NOS (nNOS) and epithelial NOS (eNOS) but not with inducible NOS (iNOS). However, the three isoforms were detected by indirect immunofluorescence (IFI), and their immunotypes varied over in vitro capacitation with cAMP-elevating agents. NO· levels (evaluated by DAF-2-DA/PI staining) increased after in vitro capacitation, and the presence of L-arginine in the capacitatin...

Research paper thumbnail of Sperm quality and seminal plasma proteins in three sheep breeds under high altitude and tropical conditions

Spanish Journal of Agricultural Research, 2018

We tested the hypothesis that sheep breed can influence the sperm quality and seminal plasma (SP)... more We tested the hypothesis that sheep breed can influence the sperm quality and seminal plasma (SP) composition and investigated any potential relationship between SP proteins and antioxidant enzyme activities (AO) with sperm quality. Ejaculates from twelve rams of three breeds were obtained during the rainy season at high altitudes, and sperm quality was automatically evaluated (CASA-Hamilton Thorne). The AO of superoxide dismutase, glutathione peroxide and glutathione reductase (GR) in SP was evaluated and total proteins were separated by SDS-PAGE. Comparative analyses of semen quality parameters between breeds revealed that Creole and Hampshire breeds had a higher sperm quality compared with Romney Marsh (p<0.05), although no difference in AO was found. GR activity was negatively correlated (p<0.05) with several kinematic variables and positively (p<0.05) with morphological abnormalities. The highest SP protein concentration was found in semen collected from Hampshire male...

Research paper thumbnail of Presence of melatonin‐catabolizing non‐specific enzymes myeloperoxidase and indoleamine 2,3‐dioxygenase in the ram reproductive tract

Reproduction in Domestic Animals, 2019

The melatonin catabolism is very complex and not completely understood. Melatonin can be metaboli... more The melatonin catabolism is very complex and not completely understood. Melatonin can be metabolized by free radical interaction, but also by pseudo-enzymatically or enzymatic pathways. We have previously detected the existence of melatonin-synthesizing enzymes and melatonin receptors MT1 and MT2 in the ram reproductive tract, thus, in order to start to elucidate melatonin catabolism in these organs, we have investigated the presence of the melatonin-catabolizing enzymes indoleamine 2,3-dioxygenase (IDO, both IDO1 and IDO2 isoforms) and myeloperoxidase (MPO) in testis, epididymis and accessory glands. Gene expression analyses by real-time PCR showed the presence of MPO, IDO1, and IDO2 in all the organs of the ram reproductive tract, and revealed that MPO is the main melatonin-catabolizing enzyme, which is mainly expressed in the testis and the bulbourethral glands (P<0.05). These results were further corroborated by immunohistochemical staining, and by western-blot. Likewise, MPO was also evidenced in epididymal and ejaculated spermatozoa by indirect immunofluorescence and western-blot. In conclusion, melatonin catabolizing enzymes MPO, IDO1, and IDO2 are expressed in the ram reproductive tract, and MPO is the most expressed one, mainly in the testis and the bulbourethral glands. The presented results warrant further studies on the function of these enzymes and their melatonin metabolizing activity.