Pub Date : 2019-10-12DOI: 10.1530/biosciprocs.17.0006
J. Gadsby, L. Rose, R. Sriperumbudur, Z. Ge
In this paper we review three intra-luteal factors and their roles in the corpus luteum (CL). Insulin-like growth factor (IGF)-I, together with its receptor and IGF-binding proteins (IGFBPs), represent an important control system in the CL. IGF-I is a product of small luteal cells and has steroidogenic (i.e. luteotrophic) actions on large luteal cells via the type I receptor, while IGFBPs (e.g. BP-2 and 3; small cells) generally inhibit IGF-Is actions. IGF-I is particularly important in early CL development (up to day 7 of the oestrous cycle) in the pig. Tumour necrosis factor (TNF)-alpha is a product of luteal macrophages that infiltrate CLs in increasing numbers as the cycle progresses. TNF-alpha has been shown to play an important role in luteolysis, but we hypothesise that in the pig, this factor plays an additional role during the mid-luteal phase (days 7-13) in promoting the acquisition of luteal sensitivity to the luteolytic actions of prostaglandin (PG)F2alpha (= luteolytic sensitivity; LS). Endothelin (ET)-1 is a product of (luteal) endothelial cells, and along with its receptors (ETA and ETB) and endothelin-converting enzyme (ECE)-1, represent an intra-luteal system that also plays a role in luteolysis, in association with PGF2alpha. Since TNF-alpha induces endothelial cells to secrete ET-1, we hypothesise that ET-1 mediates the sensitising effects of TNF-alpha on the porcine CL during the mid-luteal phase (days 7-13). Finally, we hypothesise that TNF-alpha and/or ET-1 act to up-regulate luteal protein kinase C (e.g. isoforms betaII and epsilon) activity and thereby sensitises luteal cells to PGF2alpha.
{"title":"The role of intra-luteal factors in the control of the porcine corpus luteum.","authors":"J. Gadsby, L. Rose, R. Sriperumbudur, Z. Ge","doi":"10.1530/biosciprocs.17.0006","DOIUrl":"https://doi.org/10.1530/biosciprocs.17.0006","url":null,"abstract":"In this paper we review three intra-luteal factors and their roles in the corpus luteum (CL). Insulin-like growth factor (IGF)-I, together with its receptor and IGF-binding proteins (IGFBPs), represent an important control system in the CL. IGF-I is a product of small luteal cells and has steroidogenic (i.e. luteotrophic) actions on large luteal cells via the type I receptor, while IGFBPs (e.g. BP-2 and 3; small cells) generally inhibit IGF-Is actions. IGF-I is particularly important in early CL development (up to day 7 of the oestrous cycle) in the pig. Tumour necrosis factor (TNF)-alpha is a product of luteal macrophages that infiltrate CLs in increasing numbers as the cycle progresses. TNF-alpha has been shown to play an important role in luteolysis, but we hypothesise that in the pig, this factor plays an additional role during the mid-luteal phase (days 7-13) in promoting the acquisition of luteal sensitivity to the luteolytic actions of prostaglandin (PG)F2alpha (= luteolytic sensitivity; LS). Endothelin (ET)-1 is a product of (luteal) endothelial cells, and along with its receptors (ETA and ETB) and endothelin-converting enzyme (ECE)-1, represent an intra-luteal system that also plays a role in luteolysis, in association with PGF2alpha. Since TNF-alpha induces endothelial cells to secrete ET-1, we hypothesise that ET-1 mediates the sensitising effects of TNF-alpha on the porcine CL during the mid-luteal phase (days 7-13). Finally, we hypothesise that TNF-alpha and/or ET-1 act to up-regulate luteal protein kinase C (e.g. isoforms betaII and epsilon) activity and thereby sensitises luteal cells to PGF2alpha.","PeriodicalId":87420,"journal":{"name":"Society of Reproduction and Fertility supplement","volume":"62 1","pages":"69-83"},"PeriodicalIF":0.0,"publicationDate":"2019-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44093174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-12DOI: 10.1530/biosciprocs.17.0022
S. L. Pratt, E. Sherrer, D. Reeves, S. Stice
Production of cloned pigs using somatic cell nuclear transfer (SCNT) is a repeatable and predictable procedure and multiple labs around the world have generated cloned pigs and genetically modified cloned pigs. Due to the integrated nature of the pork production industry, pork producers are the most likely to benefit and are in the best position to introduce cloning in to production systems. Cloning can be used to amplify superior genetics or be used in conjunction with genetic modifications to produce animals with superior economic traits. Though unproven, cloning could add value by reducing pig-to-pig variability in economically significant traits such as growth rate, feed efficiency, and carcass characteristics. However, cloning efficiencies using SCNT are low, but predictable. The inefficiencies are due to the intrusive nature of the procedure, the quality of oocytes and/or the somatic cells used in the procedure, the quality of the nuclear transfer embryos transferred into recipients, pregnancy rates of the recipients, and neonatal survival of the clones. Furthermore, in commercial animal agriculture, clones produced must be able to grow and thrive under normal management conditions, which include attainment of puberty and subsequent capability to reproduce. To integrate SCNT into the pork industry, inefficiencies at each step of the procedure must be overcome. In addition, it is likely that non-surgical embryo transfer will be required to deliver cloned embryos, and/or additional methods to generate high health clones will need to be developed. This review will focus on the state-of-the-art for SCNT in pigs and the steps required for practical implementation of pig cloning in animal agriculture.
{"title":"Factors influencing the commercialisation of cloning in the pork industry.","authors":"S. L. Pratt, E. Sherrer, D. Reeves, S. Stice","doi":"10.1530/biosciprocs.17.0022","DOIUrl":"https://doi.org/10.1530/biosciprocs.17.0022","url":null,"abstract":"Production of cloned pigs using somatic cell nuclear transfer (SCNT) is a repeatable and predictable procedure and multiple labs around the world have generated cloned pigs and genetically modified cloned pigs. Due to the integrated nature of the pork production industry, pork producers are the most likely to benefit and are in the best position to introduce cloning in to production systems. Cloning can be used to amplify superior genetics or be used in conjunction with genetic modifications to produce animals with superior economic traits. Though unproven, cloning could add value by reducing pig-to-pig variability in economically significant traits such as growth rate, feed efficiency, and carcass characteristics. However, cloning efficiencies using SCNT are low, but predictable. The inefficiencies are due to the intrusive nature of the procedure, the quality of oocytes and/or the somatic cells used in the procedure, the quality of the nuclear transfer embryos transferred into recipients, pregnancy rates of the recipients, and neonatal survival of the clones. Furthermore, in commercial animal agriculture, clones produced must be able to grow and thrive under normal management conditions, which include attainment of puberty and subsequent capability to reproduce. To integrate SCNT into the pork industry, inefficiencies at each step of the procedure must be overcome. In addition, it is likely that non-surgical embryo transfer will be required to deliver cloned embryos, and/or additional methods to generate high health clones will need to be developed. This review will focus on the state-of-the-art for SCNT in pigs and the steps required for practical implementation of pig cloning in animal agriculture.","PeriodicalId":87420,"journal":{"name":"Society of Reproduction and Fertility supplement","volume":"62 1","pages":"303-15"},"PeriodicalIF":0.0,"publicationDate":"2019-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47622916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-12DOI: 10.1530/biosciprocs.17.0016
P. Langendijk, N. Soede, B. Kemp
This review describes the role of boar stimuli in receptive behaviour, and the influence of boar stimuli during the follicular phase. Receptive behaviour (standing response) in an oestrous sow is elicited by boar stimuli, which can be olfactory, auditory, tactile, or visual. The relative importance of these stimuli is not clear. Individually, olfactory and tactile stimuli elicit a standing response in a variable percentage of sows, depending on the study, but not in all sows. Nevertheless, both tactile and olfactory stimuli seem essential to elicit a standing response. Contact with a boar is always more potent than combinations of boar stimuli. Intensive boar contact can cause habituation, reducing the responsiveness to boar stimuli. It is not clear how behavioural oestrus is 'prepared' at the brain level. Oestrogens are a key factor in the neuroendocrine maturation that precedes oestrus. The opioid peptide system is probably also involved. Once a sow is in oestrus, the neuroendocrinological events that are triggered by boar stimuli, and that induce a standing response, are not well understood. Oxytocin and prolactin are both released during a standing response, and again, the opioid peptide system seems to be involved. Boar stimuli are also important during the follicular phase. In gilts and sows, follicle development and (first) oestrus is advanced by boar exposure. Although there is very little evidence for this, an increase in LH secretion, caused by contact with a boar, is probably the explanation. With respect to this mechanism, habituation to boar stimuli might also play a role.
{"title":"Effects of boar stimuli on the follicular phase and on oestrous behaviour in sows.","authors":"P. Langendijk, N. Soede, B. Kemp","doi":"10.1530/biosciprocs.17.0016","DOIUrl":"https://doi.org/10.1530/biosciprocs.17.0016","url":null,"abstract":"This review describes the role of boar stimuli in receptive behaviour, and the influence of boar stimuli during the follicular phase. Receptive behaviour (standing response) in an oestrous sow is elicited by boar stimuli, which can be olfactory, auditory, tactile, or visual. The relative importance of these stimuli is not clear. Individually, olfactory and tactile stimuli elicit a standing response in a variable percentage of sows, depending on the study, but not in all sows. Nevertheless, both tactile and olfactory stimuli seem essential to elicit a standing response. Contact with a boar is always more potent than combinations of boar stimuli. Intensive boar contact can cause habituation, reducing the responsiveness to boar stimuli. It is not clear how behavioural oestrus is 'prepared' at the brain level. Oestrogens are a key factor in the neuroendocrine maturation that precedes oestrus. The opioid peptide system is probably also involved. Once a sow is in oestrus, the neuroendocrinological events that are triggered by boar stimuli, and that induce a standing response, are not well understood. Oxytocin and prolactin are both released during a standing response, and again, the opioid peptide system seems to be involved. Boar stimuli are also important during the follicular phase. In gilts and sows, follicle development and (first) oestrus is advanced by boar exposure. Although there is very little evidence for this, an increase in LH secretion, caused by contact with a boar, is probably the explanation. With respect to this mechanism, habituation to boar stimuli might also play a role.","PeriodicalId":87420,"journal":{"name":"Society of Reproduction and Fertility supplement","volume":"62 1","pages":"219-30"},"PeriodicalIF":0.0,"publicationDate":"2019-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45886112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-12DOI: 10.1530/biosciprocs.17.0004
K. Czaja
Neurophysiological mechanisms that control energy balance are reciprocally linked to those that control reproduction. Neuromorphological studies using retrograde tracing methods revealed that nerve cells within the central (CNS) and autonomic (ANS) nervous systems in different species, including the pig, are transsynaptically connected to different fat tissue depots. In the pig, neurons localised in the paraventricular nucleus, supraoptic nucleus and arcuate nucleus were infected with pseudorabies virus (PRV) 9 days after injections into both the perirenal and subcutaneous adipose tissue depots. Infected neurons were in the ventromedial nucleus, dorsomedial nucleus and preoptic area after injection of PRV into perirenal adipose tissue, while infected cells in the lateral hypothalamic area projected only to the subcutaneous adipose tissue depot. Additionally, numerous centres of the ANS innervate adipose tissue depots in the pig. Fast blue stained (FB+) neurons, which projected to the subcutaneous adipose tissue overlaying the thoracolumbar area were located in the thoraco-lumbar region of the sympathetic chain ganglia (SChG). However, neurons supplying perirenal and mesentery adipose tissue depots were found in both the SChG and prevertebral ganglia. The vast majority of labelled neurons, in both the CNS and ANS, which innervated adipose tissue depots, expressed leptin receptor (OBR) immunoreactivity. The purpose of this brief review is to establish evidence for a multisynaptic circuit of neurons, which innervate adipose tissue in the pig and demonstrate that hypothalamic nuclei and sympathetic ganglion neurons involved in reproductive processes are transsynaptically connected to different adipose tissue depots.
{"title":"Transsynaptic connections between the hypothalamus and adipose tissue: relationship to reproduction.","authors":"K. Czaja","doi":"10.1530/biosciprocs.17.0004","DOIUrl":"https://doi.org/10.1530/biosciprocs.17.0004","url":null,"abstract":"Neurophysiological mechanisms that control energy balance are reciprocally linked to those that control reproduction. Neuromorphological studies using retrograde tracing methods revealed that nerve cells within the central (CNS) and autonomic (ANS) nervous systems in different species, including the pig, are transsynaptically connected to different fat tissue depots. In the pig, neurons localised in the paraventricular nucleus, supraoptic nucleus and arcuate nucleus were infected with pseudorabies virus (PRV) 9 days after injections into both the perirenal and subcutaneous adipose tissue depots. Infected neurons were in the ventromedial nucleus, dorsomedial nucleus and preoptic area after injection of PRV into perirenal adipose tissue, while infected cells in the lateral hypothalamic area projected only to the subcutaneous adipose tissue depot. Additionally, numerous centres of the ANS innervate adipose tissue depots in the pig. Fast blue stained (FB+) neurons, which projected to the subcutaneous adipose tissue overlaying the thoracolumbar area were located in the thoraco-lumbar region of the sympathetic chain ganglia (SChG). However, neurons supplying perirenal and mesentery adipose tissue depots were found in both the SChG and prevertebral ganglia. The vast majority of labelled neurons, in both the CNS and ANS, which innervated adipose tissue depots, expressed leptin receptor (OBR) immunoreactivity. The purpose of this brief review is to establish evidence for a multisynaptic circuit of neurons, which innervate adipose tissue in the pig and demonstrate that hypothalamic nuclei and sympathetic ganglion neurons involved in reproductive processes are transsynaptically connected to different adipose tissue depots.","PeriodicalId":87420,"journal":{"name":"Society of Reproduction and Fertility supplement","volume":"62 1","pages":"45-53"},"PeriodicalIF":0.0,"publicationDate":"2019-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44840457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-12DOI: 10.1530/biosciprocs.17.0015
Olli Peltoniemi, J. Virolainen
In the wild, the pig adapts her reproductive functions according to the seasonal changes in the environment, such as the ambient temperature and availability of food. Like in other short day seasonal breeders, breeding season is favoured in the mid winter in order to provide the offspring with the best chances to survive four months later. Seasonal changes in environment are perceived mainly by the ability of the pig to recognise seasonal changes in photoperiod. This information is mediated through changes in the activity of the pineal gland to secret melatonin, essentially by the same mechanism as reported for other mammals. Stimulation of melatonin receptors located in the hypothalamus has a significant role for the release of GnRH and subsequent gonadotrophin release from the pituitary. Management and nutrition related factors determine the degree of seasonal effects on reproduction in the commercial piggery environment. Significant improvements in fertility in herds suffering from seasonal infertility are achievable by providing gilts and sows with abundant feed after mating. Attempts to alleviate the seasonal effects on fertility by applying light programs are underway and may lead to significant improvements in productivity of the domestic pig in the long run. Hormonal treatments may be somewhat effective, but not a sustainable solution to seasonal infertility. In conclusion, seasonal infertility is a photoperiod induced phenomenon that can be manipulated by changes in photoperiod and by accounting for season as a significant factor when feeding strategies are applied in commercial piggeries.
{"title":"Seasonality of reproduction in gilts and sows.","authors":"Olli Peltoniemi, J. Virolainen","doi":"10.1530/biosciprocs.17.0015","DOIUrl":"https://doi.org/10.1530/biosciprocs.17.0015","url":null,"abstract":"In the wild, the pig adapts her reproductive functions according to the seasonal changes in the environment, such as the ambient temperature and availability of food. Like in other short day seasonal breeders, breeding season is favoured in the mid winter in order to provide the offspring with the best chances to survive four months later. Seasonal changes in environment are perceived mainly by the ability of the pig to recognise seasonal changes in photoperiod. This information is mediated through changes in the activity of the pineal gland to secret melatonin, essentially by the same mechanism as reported for other mammals. Stimulation of melatonin receptors located in the hypothalamus has a significant role for the release of GnRH and subsequent gonadotrophin release from the pituitary. Management and nutrition related factors determine the degree of seasonal effects on reproduction in the commercial piggery environment. Significant improvements in fertility in herds suffering from seasonal infertility are achievable by providing gilts and sows with abundant feed after mating. Attempts to alleviate the seasonal effects on fertility by applying light programs are underway and may lead to significant improvements in productivity of the domestic pig in the long run. Hormonal treatments may be somewhat effective, but not a sustainable solution to seasonal infertility. In conclusion, seasonal infertility is a photoperiod induced phenomenon that can be manipulated by changes in photoperiod and by accounting for season as a significant factor when feeding strategies are applied in commercial piggeries.","PeriodicalId":87420,"journal":{"name":"Society of Reproduction and Fertility supplement","volume":"62 1","pages":"205-18"},"PeriodicalIF":0.0,"publicationDate":"2019-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43356479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Activation of its genome is amongst the essential task the embryo has to undertake following fertilization of the egg. In animal and plants, this activation follows a period of transcriptional silence, which is made necessary by the requirement for an almost complete and functional reprogramming of the DNA coming from both gametes. The process by which DNA is silenced, reprogrammed and reactivated is not fully understood yet but progresses are being made, especially with the help of genomic tools. This review will focus on the recent discoveries made in different animal models and more specifically on the efforts made to further characterize the event of maternal to embryonic transition in bovine embryos.
{"title":"Activation of the embryonic genome.","authors":"M. Sirard","doi":"10.5661/RDR-VII-145","DOIUrl":"https://doi.org/10.5661/RDR-VII-145","url":null,"abstract":"Activation of its genome is amongst the essential task the embryo has to undertake following fertilization of the egg. In animal and plants, this activation follows a period of transcriptional silence, which is made necessary by the requirement for an almost complete and functional reprogramming of the DNA coming from both gametes. The process by which DNA is silenced, reprogrammed and reactivated is not fully understood yet but progresses are being made, especially with the help of genomic tools. This review will focus on the recent discoveries made in different animal models and more specifically on the efforts made to further characterize the event of maternal to embryonic transition in bovine embryos.","PeriodicalId":87420,"journal":{"name":"Society of Reproduction and Fertility supplement","volume":"67 1","pages":"145-58"},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49295234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Anthony, J. D. Cantlon, K. C. Gates, S. Purcell, C. Clay
The placenta provides the means for nutrient transfer from the mother to the fetus, waste transfer from the fetus to the mother, protection of the fetus from the maternal immune system, and is an active endocrine organ. While many placental functions have been defined and investigated, assessing the function of specific genes expressed by the placenta has been problematic, since classical ablation-replacement methods are not feasible with the placenta. The pregnant sheep has been a long-standing animal model for assessing in vivo physiology during pregnancy, since surgical placement of indwelling catheters into both maternal and fetal vasculature has allowed the assessment of placental nutrient transfer and utilization, as well as placental hormone secretion, under unanesthetized-unstressed steady state sampling conditions. However, in ruminants the lack of well-characterized trophoblast cell lines and the inefficiency of creating transgenic pregnancies in ruminants have inhibited our ability to assess specific gene function. Recently, sheep and cattle primary trophoblast cell lines have been reported, and may further our ability to investigate trophoblast function and transcriptional regulation of genes expressed by the placenta. Furthermore, viral infection of the trophoectoderm layer of hatched blastocysts, as a means for placenta-specific transgenesis, holds considerable potential to assess gene function in the ruminant placenta. This approach has been used successfully to "knockdown" gene expression in the developing sheep conceptus, and has the potential for gain-of-function experiments as well. While this technology is still being developed, it may provide an efficient approach to assess specific gene function in the ruminant placenta.
{"title":"Assessing gene function in the ruminant placenta.","authors":"R. Anthony, J. D. Cantlon, K. C. Gates, S. Purcell, C. Clay","doi":"10.5661/RDR-VII-119","DOIUrl":"https://doi.org/10.5661/RDR-VII-119","url":null,"abstract":"The placenta provides the means for nutrient transfer from the mother to the fetus, waste transfer from the fetus to the mother, protection of the fetus from the maternal immune system, and is an active endocrine organ. While many placental functions have been defined and investigated, assessing the function of specific genes expressed by the placenta has been problematic, since classical ablation-replacement methods are not feasible with the placenta. The pregnant sheep has been a long-standing animal model for assessing in vivo physiology during pregnancy, since surgical placement of indwelling catheters into both maternal and fetal vasculature has allowed the assessment of placental nutrient transfer and utilization, as well as placental hormone secretion, under unanesthetized-unstressed steady state sampling conditions. However, in ruminants the lack of well-characterized trophoblast cell lines and the inefficiency of creating transgenic pregnancies in ruminants have inhibited our ability to assess specific gene function. Recently, sheep and cattle primary trophoblast cell lines have been reported, and may further our ability to investigate trophoblast function and transcriptional regulation of genes expressed by the placenta. Furthermore, viral infection of the trophoectoderm layer of hatched blastocysts, as a means for placenta-specific transgenesis, holds considerable potential to assess gene function in the ruminant placenta. This approach has been used successfully to \"knockdown\" gene expression in the developing sheep conceptus, and has the potential for gain-of-function experiments as well. While this technology is still being developed, it may provide an efficient approach to assess specific gene function in the ruminant placenta.","PeriodicalId":87420,"journal":{"name":"Society of Reproduction and Fertility supplement","volume":"67 1","pages":"119-31"},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44524325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Circannual clocks drive rhythms in reproduction and many other seasonal characteristics but the underlying control of these long-term oscillators remains a mystery. Now, we propose that circannual timing involves mechanisms that are integral to the ontogenetic life-history programme where annual transitions are generated by cell birth, death and tissue regeneration throughout the life cycle--the histogenesis hypothesis. The intrinsic cycle is then timed by cues from the environment. The concept is that in specific sites in the brain, pituitary and peripheral tissues, residual populations of progenitor cells (adult stem cells) synchronously initiate a phase of cell division to begin a cycle. The progeny cells then proliferate, migrate and differentiate, providing the substrate that drives physiological change over long time-spans (e.g. summer/winter); cell death may be required to trigger the next cycle. We have begun to characterise such a tissue-based timer in our Soay sheep model focusing on the pars tuberalis (PT) of the pituitary gland and the sub-ventricular zone of the mediobasal hypothalamus (MBH) as potential circannual pacemakers. The PT is of special interest because it is a melatonin-responsive tissue containing undifferentiated cells, strategically located at the gateway between the brain and pituitary gland. The PT also governs long-photoperiod activation of thyroid hormone dependant processes in the MBH required for neurogenesis. In sheep, exposure to long photoperiod markedly activates BrDU-labelled cell proliferation in the PT and MBH, and acts to entrain the circannual reproductive cycle. Variation in expression and co-ordination of multiple tissue timers may explain species differences in circannual rhythmicity. This paper is dedicated to the memory of Ebo Gwinner.
{"title":"Mammalian circannual pacemakers.","authors":"GA Lincoln, DG Hazlerigg","doi":"10.5661/RDR-VII-173","DOIUrl":"https://doi.org/10.5661/RDR-VII-173","url":null,"abstract":"Circannual clocks drive rhythms in reproduction and many other seasonal characteristics but the underlying control of these long-term oscillators remains a mystery. Now, we propose that circannual timing involves mechanisms that are integral to the ontogenetic life-history programme where annual transitions are generated by cell birth, death and tissue regeneration throughout the life cycle--the histogenesis hypothesis. The intrinsic cycle is then timed by cues from the environment. The concept is that in specific sites in the brain, pituitary and peripheral tissues, residual populations of progenitor cells (adult stem cells) synchronously initiate a phase of cell division to begin a cycle. The progeny cells then proliferate, migrate and differentiate, providing the substrate that drives physiological change over long time-spans (e.g. summer/winter); cell death may be required to trigger the next cycle. We have begun to characterise such a tissue-based timer in our Soay sheep model focusing on the pars tuberalis (PT) of the pituitary gland and the sub-ventricular zone of the mediobasal hypothalamus (MBH) as potential circannual pacemakers. The PT is of special interest because it is a melatonin-responsive tissue containing undifferentiated cells, strategically located at the gateway between the brain and pituitary gland. The PT also governs long-photoperiod activation of thyroid hormone dependant processes in the MBH required for neurogenesis. In sheep, exposure to long photoperiod markedly activates BrDU-labelled cell proliferation in the PT and MBH, and acts to entrain the circannual reproductive cycle. Variation in expression and co-ordination of multiple tissue timers may explain species differences in circannual rhythmicity. This paper is dedicated to the memory of Ebo Gwinner.","PeriodicalId":87420,"journal":{"name":"Society of Reproduction and Fertility supplement","volume":"67 1","pages":"171-86"},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47329795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Advances in the analyses of human and other higher eukaryotic genomes have disclosed a large fraction of the genetic material (ca 98%) which does not code for proteins. Major portion of this non-coding genome is in fact transcribed into an enormous repertoire of functional non coding RNA molecules (ncRNAs) rather than encoding any proteins. Recent fascinating and fast progress in bioinformatic, high-throughput sequencing and other biochemical approaches have fuelled rapid growth in our appreciation of the tremendous number, diversity and biological importance of these ncRNAs in the hidden layer of gene regulation both at transcriptional and post-transcriptional level. Broadly ncRNAs fall into three size classes namely, 20 nucleotides for the large family of microRNAs (miRNAs), to 25-200 nucleotides for other different families of small RNAs and finally to over thousands of nucleotides for macro ncRNAs involved in eukaryotic gene regulation. Among the ncRNAs that have revolutionized our understanding of eukaryotic gene expression, microRNAs (miRNAs) have recently been emphasized extensively with enormous potential for playing a pivotal role in disease, fertility and development. They are found to be potentially involved in various aspects of physiological regulation of reproductive tissues (testis, ovary, endometrium and oviduct), cells (sperm and oocytes) and embryonic development in addition to other body systems. Here, we review the recent work on miRNAs in details and some other small ncRNAs briefly in animal models focusing on their diverse roles in the physiology of reproductive cells and tissues together with their implications for ruminant reproductive biology.
{"title":"The noncoding genome: implications for ruminant reproductive biology.","authors":"D. Tesfaye, M. Hossain, K. Schellander","doi":"10.5661/RDR-VII-73","DOIUrl":"https://doi.org/10.5661/RDR-VII-73","url":null,"abstract":"Advances in the analyses of human and other higher eukaryotic genomes have disclosed a large fraction of the genetic material (ca 98%) which does not code for proteins. Major portion of this non-coding genome is in fact transcribed into an enormous repertoire of functional non coding RNA molecules (ncRNAs) rather than encoding any proteins. Recent fascinating and fast progress in bioinformatic, high-throughput sequencing and other biochemical approaches have fuelled rapid growth in our appreciation of the tremendous number, diversity and biological importance of these ncRNAs in the hidden layer of gene regulation both at transcriptional and post-transcriptional level. Broadly ncRNAs fall into three size classes namely, 20 nucleotides for the large family of microRNAs (miRNAs), to 25-200 nucleotides for other different families of small RNAs and finally to over thousands of nucleotides for macro ncRNAs involved in eukaryotic gene regulation. Among the ncRNAs that have revolutionized our understanding of eukaryotic gene expression, microRNAs (miRNAs) have recently been emphasized extensively with enormous potential for playing a pivotal role in disease, fertility and development. They are found to be potentially involved in various aspects of physiological regulation of reproductive tissues (testis, ovary, endometrium and oviduct), cells (sperm and oocytes) and embryonic development in addition to other body systems. Here, we review the recent work on miRNAs in details and some other small ncRNAs briefly in animal models focusing on their diverse roles in the physiology of reproductive cells and tissues together with their implications for ruminant reproductive biology.","PeriodicalId":87420,"journal":{"name":"Society of Reproduction and Fertility supplement","volume":"67 1","pages":"73-93"},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70827806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sheep are seasonal breeders and reproductive status is controlled by photoperiod. Recent recognition of the significant role for kisspeptin and gonadotropin inhibitory hormone (GnIH) in the regulation of gonadotropin releasing hormone (GnRH) cells has provided a new perspective in the seasonal regulation of reproductive activity. Virtually all kisspeptin cells express estrogen receptors and kisspeptin is a potent stimulator of GnRH secretion. Thus, kisspeptin cells provide a conduit by which changes in estrogen feedback effects may be exerted upon GnRH cells. Changes in the activity of kisspeptin cells with season indicate a major role in the seasonal changes in reproductive activity in the ewe. GnIH is an inhibitor of reproductive function and there is mounting evidence that changing activity of this system is also an important determinant of reproductive status. Reciprocal changes in kisspeptin and GnIH activity explain seasonal changes in the function of GnRH cells.
{"title":"The role of kisspeptin and gonadotropin inhibitory hormone (GnIH) in the seasonality of reproduction in sheep.","authors":"Iain J. Clarke, Jeremy T. Smith","doi":"10.5661/RDR-VII-159","DOIUrl":"https://doi.org/10.5661/RDR-VII-159","url":null,"abstract":"Sheep are seasonal breeders and reproductive status is controlled by photoperiod. Recent recognition of the significant role for kisspeptin and gonadotropin inhibitory hormone (GnIH) in the regulation of gonadotropin releasing hormone (GnRH) cells has provided a new perspective in the seasonal regulation of reproductive activity. Virtually all kisspeptin cells express estrogen receptors and kisspeptin is a potent stimulator of GnRH secretion. Thus, kisspeptin cells provide a conduit by which changes in estrogen feedback effects may be exerted upon GnRH cells. Changes in the activity of kisspeptin cells with season indicate a major role in the seasonal changes in reproductive activity in the ewe. GnIH is an inhibitor of reproductive function and there is mounting evidence that changing activity of this system is also an important determinant of reproductive status. Reciprocal changes in kisspeptin and GnIH activity explain seasonal changes in the function of GnRH cells.","PeriodicalId":87420,"journal":{"name":"Society of Reproduction and Fertility supplement","volume":"67 1","pages":"159-69"},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70827677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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