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August 1989 - November 1997
August 2000 - present
Publications
Publications (87)
Kisspeptin is a major regulator of gonadotropin secretion in pigs. Previously, CRISPR/Cas9 knockout of KISS1 was used to develop a mosaic parental line of pigs to generate offspring that would not need castration due to loss of kisspeptin. The current goal was to characterize growth and reproductive development of F1 pigs from this parental line. B...
Reproduction is classically controlled by gonadotropin-releasing hormone (GnRH-I) and its receptor (GnRHR-I) within the brain. In pigs, a second form (GnRH-II) and its specific receptor (GnRHR-II) are also produced, with greater abundance in peripheral vs. central reproductive tissues. The binding of GnRH-II to GnRHR-II has been implicated in the a...
Gonadotropin-releasing hormone (GnRH1) and its receptor (GnRHR1) drive reproduction by regulating gonadotropins. Another form, GnRH2, and its receptor (GnRHR2), also exist in mammals. In humans, GnRH2 and GnRHR2 genes are present, but coding errors in the GnRHR2 gene are predicted to hinder full-length protein production. Nonetheless, mounting evid...
We generated kisspeptin knockout (KISS1-/- ) pigs exhibiting hypogonadotropic hypogonadism and pubertal failure. Humans and rodents with inactivating KISS1 mutations exhibit increased gonadotropin secretion in response to GnRH and kisspeptin analogs, but it is unknown if KISS1-/- pigs respond similarly. Our goal was to define endocrine responses of...
The biological role of kisspeptin in the reproduction of swine has been far less studied than in other species. In the porcine hypothalamus, kisspeptin is coexpressed with neurokinin B and dynorphin in KNDy neurons. Although kisspeptin-stimulated secretion of gonadotropin hormones in gilts was established early, increased expression of hypothalamic...
In swine production, boars are castrated to prevent boar taint from testicular androgens and skatole accumulation in fat. Kisspeptin (KISS1) regulates secretion of gonadotropins and gonadal steroids. We used boars from our line of KISS1-/-pigs (10.3389/fgene.2022.1078991) to understand how loss of KISS1 function affects compounds causing boar taint...
The pig represents the only livestock mammal capable of producing a functional protein for the second mammalian form of gonadotropin-releasing hormone (GnRH-II) and its receptor (GnRHR-II). To examine the role of GnRH-II and its receptor in pig reproduction, we produced a unique swine line with ubiquitous knockdown of endogenous GnRHR-II levels (Gn...
Pigs are the only livestock species encoding functional proteins for both the second form of gonadotropin-releasing hormone (GnRH-II) and its receptor (GnRHR-II). Previously, we determined that GnRHR-II localizes to the connecting piece of ejaculated sperm, whereas GnRH-II is present within seminal plasma, suggesting an autocrine/paracrine interact...
Swine are the only livestock which produce both the second mammalian form of GnRH (GnRH-II) and its cognate receptor (GnRHR-II). Mounting evidence suggests that GnRH-II and its receptor do not stimulate gonadotropin secretion in vivo but instead elicit testicular steroidogenesis in an autocrine/paracrine manner. To elucidate the role of this novel...
Pigs are the only livestock species encoding functional proteins for both the second form of gonadotropin-releasing hormone (GnRH-II) and its receptor (GnRHR-II), which are uniquely expressed in reproductive and non-reproductive tissues. To examine the physiological role of the GnRH-II/GnRHR-II system, we produced a swine line with reduced endogeno...
Since genetic engineering of pigs can benefit both biomedicine and agriculture, selecting a suitable gene promoter is critically important. The cytomegalovirus (CMV) promoter, which can robustly drive ubiquitous transgene expression, is commonly used at present, yet recent reports suggest tissue-specific activity in the pig. The objective of this s...
The second mammalian form of GnRH (GnRH-II) and its receptor (GnRHR-II) are produced in only one livestock species, the pig. Paradoxically, the physiological interaction of GnRH-II with its receptor does not stimulate gonadotropin secretion. Instead, both are abundantly produced within the testis and have been implicated in autocrine/paracrine regu...
Semen quality has a dramatic impact on reproductive efficiency in the swine industry, influencing both conception rate and litter size. The objective of this study was to assess whether the presence of varicocele hinders semen quality in both thermoneutral and heat stress conditions. At approximately 6 months of age, ultrasonography was used to mea...
Pigs are the only livestock species encoding a functional protein for both the second isoform of gonadotrophin-releasing hormone (GnRH-II) and its cognate receptor (GnRHR-II). Unlike the classical GnRH system (GnRH-I and GnRHR-I), GnRH-II and GnRHR-II are abundantly produced in porcine testes. Moreover, GnRH-II binding its receptor on Leydig cells...
The second mammalian form of GnRH (GnRH-II) and its cognate receptor (GnRHR-II) are produced in only one livestock species, the pig. Paradoxically, however, the interaction of GnRH-II with its receptor does not stimulate gonadotropin secretion. Instead, both are abundantly produced within the porcine testis, suggesting an autocrine/paracrine intera...
The second form of GnRH (GnRH-II) and its receptor (GnRHR-II) are produced in only one livestock species, the pig. Paradoxically, their interaction does not stimulate gonadotropin secretion. Instead, both have been implicated in autocrine/paracrine regulation of steroidogenesis. To elucidate their role in ovarian function, our laboratory generated...
Background
The advent of genetically engineered pig production has revealed a wide array of opportunities to enhance both biomedical and agricultural industries. One powerful method to develop these models is transgenesis; however, selection of a suitable promoter to drive transgene expression is critical. The cytomegalovirus (CMV) promoter is the...
Exosomes participate in cell-to-cell communication, facilitated by the transfer of RNAs, proteins and lipids from donor to recipient cells. Exosomes and their RNA cargos do not exclusively originate from endogenous synthesis but may also be obtained from dietary sources such as the inter-species transfer of exosomes and RNAs in bovine milk to human...
Paradoxically, the second mammalian GnRH isoform (GnRH-II) and its receptor (GnRHR-II) are not physiological regulators of gonadotropin secretion. Instead, our data suggests that both are abundantly produced in the porcine testis and mediate testosterone secretion, independent of luteinizing hormone (LH). To further study the role of this system, o...
Gonadotropin-releasing hormone 1 (GnRH1) and its receptor (GnRHR1) drive mammalian reproduction via regulation of the gonadotropins. Yet, a second form of GnRH (GnRH2) and its receptor (GnRHR2) also exist in mammals. GnRH2 has been completely conserved throughout 500 million years of evolution, signifying high selection pressure and a critical biol...
Swine are the only livestock species that produce both the second mammalian isoform of gonadotropin-releasing hormone (GNRH2) and its receptor (GNRHR2). Previously, we reported that GNRH2 and GNRHR2 mediate LH-independent testosterone secretion from porcine testes. To further explore this ligand-receptor complex, a pig model with reduced GNRHR2 exp...
Widespread use of artificial insemination in swine requires millions of doses of boar semen each year. Subfertility of boars remains a major constraint, which can impact the reproductive efficiency of thousands of sows, so a better understanding of testicular function is needed in order to develop methods to improve semen production. With this in m...
Boar subfertility represents a major limitation to swine production , reducing conception rate and litter size. Critical to reproductive function, the classical form of GnRH (GnRH1) promotes secretion of the gonadotropins; however, the second mammalian isoform (GnRH2) is a poor stimulator of gonadotropin release. A receptor specific to GnRH2 (GnRHR...
Boar subfertility represents a major limitation to swine production , reducing conception rate and litter size. Critical to reproductive function, the classical form of GnRH (GnRH1) promotes secretion of the gonadotropins; however, the second mammalian isoform (GnRH2) is a poor stimulator of gonad-otropin release. A receptor specific to GnRH2 (GnRH...
Mechanisms governing the timing of puberty in pigs are poorly understood. A genome-wide association study for age at first estrus in pigs identified candidate genes including neuropeptide FF receptor 2 (NPFFR2), which is a putative receptor for RFamide-related peptides (RFRP). RFRP has been shown to negatively regulate secretion of reproductive hor...
The second mammalian GnRH isoform (GnRH-II) and its specific receptor (GnRHR-II) are ubiquitously expressed, with elevated levels in the testis. Gene coding errors prevent their production in many species, but both genes are functional in swine. We demonstrated that GnRHR-II localizes to porcine Leydig cells, and exogenous GnRH-II robustly stimulat...
Case studies are a useful teaching tool in professional physiology courses but are not commonly utilized in the undergraduate classroom. Notably, others have demonstrated that case-based reasoning enhances information retention in a veterinary physiology course. Thus, case studies may be an undervalued teaching tool for undergraduate physiology cou...
Unlike the classical gonadotropin-releasing hormone (GnRH-I), the second mammalian GnRH isoform (GnRH-II; His5, Trp7, Tyr8) is a poor stimulator of gonadotropin secretion. In addition, GnRH-II is ubiquitously expressed, with transcript levels highest in tissues outside of the brain. A receptor specific to GnRH-II (GnRHR-II) has been identified in m...
Background:
Binding of gonadotropin-releasing hormone (GnRH) to its receptor (GnRHR) on gonadotropes within the anterior pituitary gland is essential to reproduction. In pigs, the GnRHR gene is also located near a genetic marker for ovulation rate, a primary determinant of prolificacy. We hypothesized that pituitary expression of the GnRHR gene is...
Case studies can be a useful teaching tool but are not commonly utilized in undergraduate courses. Notably, others have demonstrated that case-based reasoning enhances information retention in a veterinary physiology course. Thus, case studies may be an undervalued teaching tool for undergraduate physiology courses. Accordingly, our objective was t...
The second mammalian isoform of gonadotropin-releasing hormone (GnRH-II) functions quite differently from the classical form (GnRH-I) as it is a poor stimulator of gonadotropin release. Unlike most species, a functional GnRHR-II has been identified in swine. Our laboratory detected GnRHR-IIs on Leydig cells and demonstrated that GnRH-II stimulates...
Unlike the classical gonadotropin-releasing hormone (GnRH-I), the second mammalian isoform of GnRH (GnRH-II) is ubiquitously expressed with the most abundant transcript levels found in tissues outside of the hypothalamus. Moreover, GnRH-II is only an inefficient stimulator of gonadotropin release. Interestingly, the pig represents the only livestoc...
Unlike the classical gonadotropin-releasing hormone (GNRH1), the second mammalian isoform (GNRH2) is an ineffective stimulant of gonadotropin release. Species that produce GNRH2 may not maintain a functional GNRH2 receptor (GNRHR2) due to coding errors. A full length GNRHR2 gene has been identified in swine, but its role in reproduction requires fu...
Regulation of gonadotropin-releasing hormone (GnRH) receptor (GnRHR) numbers on the surface of gonadotropes within the anterior pituitary gland represents a critical point for control of reproductive function. Binding of the ligand, GnRH, to its receptor regulates the release of follicle stimulating hormone (FSH) and luteinizing hormone (LH) and th...
The second mammalian isoform of gonadotropin-releasing hormone (GnRH-II) functions quite differently from the classical form (GnRH-I), being an ineffective modulator of gonadotropin release. Not all species that produce GnRH-II maintain a full length GnRH-II receptor (GnRHR-II). Instead, GnRH-II can mediate its action via the GnRH-I receptor (GnRHR...
Unlike the native form of gonadotropin-releasing hormone (GnRH-I), the second isoform of GnRH (GnRH-II) is highly conserved throughout evolution and is ubiquitously expressed. The pig represents one of the few species possessing coding sequence for a functional receptor specific to GnRH-II (GnRHR-II). Binding of GnRH-II to its receptor has been lin...
The second mammalian isoform of gonadotropin-releasing hormone (GnRH-II) functions quite differently from the classical form (GnRH-I), being an ineffective modulator of gonadotropin release. Not all species that produce GnRH-II maintain a full length GnRH-II receptor (GnRHR-II). Instead, GnRH-II can mediate its action via the GnRH-I receptor (GnRHR...
The second mammalian isoform of GnRH (GnRH-II) is highly conserved from bony fish to humans. However, coding sequence for the receptor specific to this ligand contains reading errors in many species, suggesting the inability to produce a functional receptor. In contrast, the porcine GnRH-II receptor gene contains the appropriate sequence to produce...
The binding of GnRH to its receptor results in the synthesis and secretion of the gonadotropins, as well as stimulation of the gene encoding its own receptor. Thus, the interaction between GnRH and GnRHR represents a central point for regulation of reproductive function. Glucocorticoids can alter reproduction by reducing GnRH responsiveness of gona...
Environmental issues have expanded to the forefront of livestock production systems. Air and water quality, human health concerns, and pathogens associated with manure are important issues being examined in swine production systems. In addition, methodologies to reduce and(or) eliminate these issues have become important avenues of scientific resea...
Gonadotropin-releasing hormone (GnRH) II has been implicated in the interaction between female energy balance and reproductive function, in addition to an anti-proliferative/apoptotic role in cancer cell lines. Specifically, administration of GnRH II to underfed female mice or musk shrews rescued mating behavior. Moreover, endometrial and ovarian c...
Type II gonadotropin-releasing hormone (GnRH II) is highly conserved from bony fish to man, although the physiological role of GnRH II is not clearly understood. In mammalian species, it has been linked to the interaction between energy balance and mating behavior in females as well as anti-proliferative effects in cancer cell lines. Structurally,...
The binding of GnRH to its receptor results in the synthesis and secretion of the gonadotropins, as well as stimulation of the gene encoding its own receptor. Thus, the interaction between GnRH and GnRHR represents a central point for regulation of reproductive function. Glucocorticoids can alter reproduction by reducing GnRH responsiveness of gona...
Marginal biotin deficiency develops in 50% of pregnant women. Studies in mice showed that biotin deficiency may cause fetal malformations, including cleft palate and abnormal skeletal development. Here we used DNA microarrays and computational biology approaches to identify biotin‐dependent cell signaling networks that play roles in causing these m...
Binding of GnRH to its receptor represents a central point for regulation of reproduction in mammals. Recently, a new mammalian GnRH decapeptide has been identified, GnRH-II, differing from the classical peptide, GnRH-I, by three amino acids. Consistent with this, GnRH-II elicits its effects via an alternative receptor isoform, type II GnRH recepto...
The interaction between GnRH and its receptor is critical to regulation of reproductive function. Additionally, the porcine GnRH receptor (GnRHR) gene is located near a quantitative trait locus for ovulation rate. Thus, the GnRHR gene represents both a physiological and positional candidate for genes influencing ovulation rate. Our laboratory has c...
Cows were treated with two progestin concentrations to develop ovulatory follicles exposed to different hormone environments. Cows were assigned to Control Group receiving a CIDR for 7 days (4-6 ng/ml of progestin), or to MGA-14 Group receiving 5mg/head/day of MGA for 14 days (< 1 ng of progestin). Our hypothesis was that the MGA-14 treatment would...
Successful freezing, or cryopreservation, of embryos could greatly impact the pork industry, serving as a tool for conservation of valuable germplasm and enhancing biosecurity for transfer of genetic material. Pig embryos are very sensitive to cooling and few reports have shown successful developmental rates following freezing. The objectives of th...
Litter size plays a major role in the economics of pork production. Even modest increases in average litter size can have considerable effects on overall profitability. Two major components of litter size – ovulation rate and embryonic survival – have been used in a selection index project ongoing for several generations at the University of Nebras...
Development of improved protocols for cryopreservation of zona pellucida-intact porcine embryos could greatly impact the swine industry. Our aim was to investigate in vitro development following cryopreservation of embryos from Chinese Meishan (M) and occidental white cross (WC) breeds using a modified protocol described previously (Misumi K et al....
The interaction between GnRH and its receptor on gonadotropes within the anterior pituitary gland represents a key point for regulation of the reproduction. In addition, GnRH can act in multiple extrapituitary tissues via autocrine/paracrine mechanisms. Protein for GnRH and mRNA for both GnRH and its receptor have been detected in human uterine end...
Porcine reproductive and respiratory syndrome virus (PRRSv) is known to cause venereal transmission of the disease via natural or artificial breeding and this constitutes a significant risk to AI programs in modern swine production. The objectives of this study were to determine the effectiveness of a novel density gradient centrifugation method in...
Placental transfer of nutrients and secretion of hormones is essential for normal fetal development.
To determine whether biotin supply affects biotin homeostasis, proliferation rates, and progesterone secretion in placenta cells.
JAr choriocarcinoma cells were cultured in media containing deficient (25 pmol/L), physiological (250 pmol/L), or pharm...
Litter size plays a major role in the economics of swine production. Even modest increases in average litter size can have considerable effects on overall profitability. Two major components of litter size, 1) ovulation rate, and 2) embryonic survival, have been used in a selection index project ongoing for several generations at the University of...
Here the hypothesis was tested that monocarboxylate transporters (MCT) mediate biotin transport in human lymphoid cells. Uptake of [(3)H]biotin was measured in human lymphoid cells [peripheral blood mononuclear cells (PBMC) and Jurkat cells] under conditions known to affect MCT-mediated transport. When biotin uptake into PBMC was measured in the pr...
Reproductive function is dependent on the interaction between GnRH and its cognate receptor found on gonadotrope cells of the anterior pituitary gland. GnRH activation of the GnRH receptor (GnRHR) is a potent stimulus for increased expression of multiple genes including the gene encoding the GnRHR itself. Thus, homologous regulation of the GnRHR is...
White, B.R., Gerfen, R.W., Walters, E.M. and Wheeler, M.B. 2000. Comparisons of culture of Chinese Meishan with Yorkshire pig embryos in vitro: effects of protein supplementation and development. J. Appl. Anim. Res., 17: 169–184.
Three experiments were designed to evaluate modifications in a culture system for Chinese Meishan pig embryos. The objec...
Homologous regulation of GnRH receptor (GnRHR) gene expression is an established mechanism for controlling the sensitivity of gonadotropes to GnRH. We have found that expression of the GnRHR gene in the gonadotrope-derived alpha T3-1 cell line is mediated by a tripartite enhancer that includes a consensus activator protein-1 (AP-1) element, a bindi...
High production of milk and its components are necessary to allow maximal growth of developing pigs. In this study, transgenic pigs were produced containing the alpha-lactalbumin gene, whose product is a potential limiting component in the production of milk. Two lines of transgenic pigs were produced to analyze the effects that overproduction of t...
High production of milk and its components are necessary to allow maximal growth of developing pigs. In this study, transgenic pigs were produced containing the α-lactalbumin gene, whose product is a potential limiting component in the production of milk. Two lines of transgenic pigs were produced to analyze the effects that overproduction of the m...
Experiments were designed to examine: 1) age at puberty in Chinese Meishan (Ms) and Yorkshire (Y) gilts, 2) litter size in Ms and Y gilts and 3) ejaculate characteristics in Ms and Y boars. Ms gilts reached sexual maturity 105 da earlier than Y gilts and Ms gilts were in estrus almost 1 da longer than Y gilts for their first, second and third estru...
Two studies were designed to examine ovulation rate, uterine and fetal interactions, and reproductive age in Chinese Meishan (Ms) and Yorkshire (Y) gilts. In Experiment 1, ten Ms, ten Ms × Y, ten Y × Ms and ten Y females were mated at third estrus to Y, Ms × Y, Y × Ms and Ms sires, respectively, so that fetuses were 12 Ms and 12 Y. Gilts were slaug...
Five barrows and five gilts of each of two breeds (Meishan [Ms] and Yorkshire [Y]) were slaughtered at birth and at 41, 71, 123, and 171 d of age and five gilts of each breed were slaughtered at 260 d of age. Major organ and visceral weights were obtained immediately postmortem (PM), whereas carcass characteristics, carcass composition, femur measu...
Semen characteristics of Chinese Fengjing, CHinese Meishan and American Yorkshire boars were examined. Samples were collected from 24 boars: 6 Fengjing, 12 Meishan and 6 Yorkshire. Three semen characteristics and 6 biochemical evaluations of semen or seminal plasma were analyzed. The whole semen parameters measured were gelatinous (gel) and gel-fre...
Effects of porcine somatotropin (pST) on growth and carcass characteristics of Meishan (Ms) and Yorkshire (Y) barrows given 3 mg of pST or saline daily were determined for two end points. First, 26 Ms and 26 Y barrows were treated from 119 d of age until the Y barrows reached 108 kg. Second, another 18 Ms barrows were treated to 108 kg BW. Age- and...
Studies on the ovulation rate, prenatal survival and litter size of Chinese Meishan pigs have given widely divergent results depending on the extent of inbreeding of the animals, their original genetic diversity, the age and parity, and the conditions of management. To obtain meaningful results, it is necessary to characterize the population under...