The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
John P. Mcmurtry - One of the best experts on this subject based on the ideXlab platform.
-
Communication in Genomics and Proteomics Characterization of turkey and chicken ghrelin genes, and regulation of ghrelin and ghrelin receptor mRNA levels in broiler chickens
2006Co-Authors: Mark P. Richards, Stephen M. Poch, John P. McmurtryAbstract:Ghrelin, a peptide hormone produced by the stomach in mammals, stimulates growth hormone release and food intake. Recently, ghrelin was identiWed and characterized in chicken Proventriculus and shown to stimulate growth hormone release but inhibit feed intake. The purpose of this work was to identify and further characterize the ghrelin gene in chickens and in turkeys. Using molecular cloning techniques we have sequenced cDNAs corresponding to chicken (White Leghorn) and turkey ghrelin mRNAs. A total of 844 (chicken) or 869 (turkey) bases including the complete coding regions (CDS), and the 5- and 3-untranslated regions (UTRs) were determined. Nucleotide sequence (CDS) predicted a 116 amino acid precursor protein (preproghrelin) for both the chicken and the turkey that demonstrated complete conservation of an N-terminal ‘active core’ (GSSF) including a serine (position 3 of the mature hormone) known to be a modiWcation (acylation) site important for ghrelin bioactivity. Additional nucleotide sequence was found in the 5-UTRs of both Leghorn and turkey cDNAs that was not present in broilers or the red jungle fowl. The turkey ghrelin gene, sequenced from genomic DNA templates, contained Wve exons and four introns, a structure similar to mammalian and chicken ghrelin genes. Ghrelin was highly expressed in Proventriculus with much lower levels of expression in other tissues such as pancreas, brain, and intestine. RT-PCR was used to quantify ghrelin mRNA levels relative to 18S rRNA in 3-week-old male broiler chickens. The level of ghrelin mRNA increased in Proventriculus in response to fasting but did not decline with subsequent refeeding. Plasma ghrelin levels did not change signiWcantly in response to fasting or refeeding and did not appear to reXect changes in Proventriculus ghrelin mRNA levels. Ghrelin mRNA levels declined in broiler pancreas after a 48 h fast and increased upon refeeding. Expression of the gene encoding the receptor for ghrelin (growth hormone secretagogue receptor, GHS-R) and a variant form was detected in a variety of tissues collected from 3-week-old male broiler chickens possibly suggesting autocrine/paracrine eVects. These results oVer new information about the avian ghrelin and ghrelin receptor genes and the potential role that this system might play in regulating feed intake and energy balance in poultry. Published by Elsevier Inc.
-
Characterization of turkey and chicken ghrelin genes, and regulation of ghrelin and ghrelin receptor mRNA levels in broiler chickens.
General and comparative endocrinology, 2005Co-Authors: Mark P. Richards, Stephen M. Poch, John P. McmurtryAbstract:Ghrelin, a peptide hormone produced by the stomach in mammals, stimulates growth hormone release and food intake. Recently, ghrelin was identified and characterized in chicken Proventriculus and shown to stimulate growth hormone release but inhibit feed intake. The purpose of this work was to identify and further characterize the ghrelin gene in chickens and in turkeys. Using molecular cloning techniques we have sequenced cDNAs corresponding to chicken (White Leghorn) and turkey ghrelin mRNAs. A total of 844 (chicken) or 869 (turkey) bases including the complete coding regions (CDS), and the 5'- and 3'-untranslated regions (UTRs) were determined. Nucleotide sequence (CDS) predicted a 116 amino acid precursor protein (preproghrelin) for both the chicken and the turkey that demonstrated complete conservation of an N-terminal 'active core' (GSSF) including a serine (position 3 of the mature hormone) known to be a modification (acylation) site important for ghrelin bioactivity. Additional nucleotide sequence was found in the 5'-UTRs of both Leghorn and turkey cDNAs that was not present in broilers or the red jungle fowl. The turkey ghrelin gene, sequenced from genomic DNA templates, contained five exons and four introns, a structure similar to mammalian and chicken ghrelin genes. Ghrelin was highly expressed in Proventriculus with much lower levels of expression in other tissues such as pancreas, brain, and intestine. RT-PCR was used to quantify ghrelin mRNA levels relative to 18S rRNA in 3-week-old male broiler chickens. The level of ghrelin mRNA increased in Proventriculus in response to fasting but did not decline with subsequent refeeding. Plasma ghrelin levels did not change significantly in response to fasting or refeeding and did not appear to reflect changes in Proventriculus ghrelin mRNA levels. Ghrelin mRNA levels declined in broiler pancreas after a 48 h fast and increased upon refeeding. Expression of the gene encoding the receptor for ghrelin (growth hormone secretagogue receptor, GHS-R) and a variant form was detected in a variety of tissues collected from 3-week-old male broiler chickens possibly suggesting autocrine/paracrine effects. These results offer new information about the avian ghrelin and ghrelin receptor genes and the potential role that this system might play in regulating feed intake and energy balance in poultry.
Flavio Roces - One of the best experts on this subject based on the ideXlab platform.
-
The control of the Proventriculus in the honeybee (Apis mellifera carnica L.) I. A dynamic process influenced by food quality and quantity
Journal of insect physiology, 2002Co-Authors: Jasmina Blatt, Flavio RocesAbstract:The control of crop emptying in foraging honeybees was investigated in individuals trained to collect defined amounts of sugar solutions. Following feeding, they were dissected after fixed periods of time in order to measure crop content and haemolymph sugar titers. Between feeding and dissection, the metabolic rate of every investigated forager was measured using open-flow respirometry, so as to assess the effects of both food quality (concentration, molarity and viscosity of the fed sugar solution) and food quantity on the transport rate through the Proventriculus. The sugar transport rate through the Proventriculus was observed to be mainly dependent on the metabolic expenditure of the individual. Bee foragers were able to precisely adjust the sugar transport rate to their metabolic rates, but under certain conditions, an excess of sugars was transported through the Proventriculus, more than needed to cover the bee's energetic demands. This excess depended on the nutritive value and quantity of the fed sugar solution, and on the time after feeding. It did not depend on the metabolic rate of the bee, the molarity, or the viscosity of the fed sugar solution. As long as the bees did not exhaust their crop contents, the haemolymph sugar titers were unaffected by this excess amount transported, by the time after feeding, the concentration and the viscosity of the fed sugar solution. For all feeding conditions assayed, the haemolymph trehalose titer remained constant, while the titers of other haemolymph sugars varied. It is suggested that the trehalose concentration in the haemolymph is regulated in honeybees, and that it represents the controlled variable in the feedback loop responsible for the transport rate through the Proventriculus.
-
The control of the Proventriculus in the honeybee (Apis mellifera carnica L.) II. Feedback mechanisms.
Journal of insect physiology, 2002Co-Authors: Jasmina Blatt, Flavio RocesAbstract:The mechanisms underlying the control of solution transport rates through the Proventriculus in foraging honeybees were investigated in individuals trained to collect defined amounts of sugar solutions. Following feeding, bees were injected either with metabolisable (glucose, fructose, trehalose), or non-metabolisable (sorbose) sugars, in order to distinguish between haemolymph osmolarity and haemolymph sugar levels as factors controlling the solution transport rates through the Proventriculus. After a fixed period, workers were dissected in order to measure crop content and haemolymph sugar titers. Between feeding and dissection, the metabolic rate of every investigated forager was measured using open-flow respirometry. Bees injected with metabolisable sugars 15 min after feeding were observed to reduce their solution transport rates through the Proventriculus, but injection of non-metabolisable sugars had no influence on them. This suggests that the solution transport rate through the Proventriculus is controlled by the concentration of metabolisable compounds in the haemolymph, and not by the haemolymph osmolarity. A period of 10 min after injection of metabolisable sugars was enough to observe reduced solution transport rates. However, if bees were injected only 5 min after feeding, no reduced solution transport rates were observed 10 min after injection.
-
Haemolymph sugars and the control of the Proventriculus in the honey bee Apis mellifera.
Journal of insect physiology, 1999Co-Authors: Flavio Roces, Jasmina BlattAbstract:Crop emptying and rectal filling rates were investigated in bees trained to collect defined amounts of sucrose solution. Crop emptying rates strongly depended on the sucrose concentration of the collected solution. There was a close match between the energy expenditure of the bees and the amount of sucrose transported through the Proventriculus, irrespective of the fluid dilution. Results indicated that the controlling variable was the amount of sucrose flowing through the Proventriculus rather than the volume flow. In order to distinguish between haemolymph osmolality and haemolymph carbohydrate levels as factors controlling the activity of the Proventriculus, bees were injected with either metabolizable or non-metabolizable carbohydrates. Only the injection of metabolizable carbohydrates modulated the activity of the Proventriculus, indicating that the titers of metabolizable carbohydrates are involved in the feedback loop controlling crop emptying, and that haemolymph osmolality alone does not influence the activity of the Proventriculus.
Jasmina Blatt - One of the best experts on this subject based on the ideXlab platform.
-
The control of the Proventriculus in the honeybee (Apis mellifera carnica L.) I. A dynamic process influenced by food quality and quantity
Journal of insect physiology, 2002Co-Authors: Jasmina Blatt, Flavio RocesAbstract:The control of crop emptying in foraging honeybees was investigated in individuals trained to collect defined amounts of sugar solutions. Following feeding, they were dissected after fixed periods of time in order to measure crop content and haemolymph sugar titers. Between feeding and dissection, the metabolic rate of every investigated forager was measured using open-flow respirometry, so as to assess the effects of both food quality (concentration, molarity and viscosity of the fed sugar solution) and food quantity on the transport rate through the Proventriculus. The sugar transport rate through the Proventriculus was observed to be mainly dependent on the metabolic expenditure of the individual. Bee foragers were able to precisely adjust the sugar transport rate to their metabolic rates, but under certain conditions, an excess of sugars was transported through the Proventriculus, more than needed to cover the bee's energetic demands. This excess depended on the nutritive value and quantity of the fed sugar solution, and on the time after feeding. It did not depend on the metabolic rate of the bee, the molarity, or the viscosity of the fed sugar solution. As long as the bees did not exhaust their crop contents, the haemolymph sugar titers were unaffected by this excess amount transported, by the time after feeding, the concentration and the viscosity of the fed sugar solution. For all feeding conditions assayed, the haemolymph trehalose titer remained constant, while the titers of other haemolymph sugars varied. It is suggested that the trehalose concentration in the haemolymph is regulated in honeybees, and that it represents the controlled variable in the feedback loop responsible for the transport rate through the Proventriculus.
-
The control of the Proventriculus in the honeybee (Apis mellifera carnica L.) II. Feedback mechanisms.
Journal of insect physiology, 2002Co-Authors: Jasmina Blatt, Flavio RocesAbstract:The mechanisms underlying the control of solution transport rates through the Proventriculus in foraging honeybees were investigated in individuals trained to collect defined amounts of sugar solutions. Following feeding, bees were injected either with metabolisable (glucose, fructose, trehalose), or non-metabolisable (sorbose) sugars, in order to distinguish between haemolymph osmolarity and haemolymph sugar levels as factors controlling the solution transport rates through the Proventriculus. After a fixed period, workers were dissected in order to measure crop content and haemolymph sugar titers. Between feeding and dissection, the metabolic rate of every investigated forager was measured using open-flow respirometry. Bees injected with metabolisable sugars 15 min after feeding were observed to reduce their solution transport rates through the Proventriculus, but injection of non-metabolisable sugars had no influence on them. This suggests that the solution transport rate through the Proventriculus is controlled by the concentration of metabolisable compounds in the haemolymph, and not by the haemolymph osmolarity. A period of 10 min after injection of metabolisable sugars was enough to observe reduced solution transport rates. However, if bees were injected only 5 min after feeding, no reduced solution transport rates were observed 10 min after injection.
-
Haemolymph sugars and the control of the Proventriculus in the honey bee Apis mellifera.
Journal of insect physiology, 1999Co-Authors: Flavio Roces, Jasmina BlattAbstract:Crop emptying and rectal filling rates were investigated in bees trained to collect defined amounts of sucrose solution. Crop emptying rates strongly depended on the sucrose concentration of the collected solution. There was a close match between the energy expenditure of the bees and the amount of sucrose transported through the Proventriculus, irrespective of the fluid dilution. Results indicated that the controlling variable was the amount of sucrose flowing through the Proventriculus rather than the volume flow. In order to distinguish between haemolymph osmolality and haemolymph carbohydrate levels as factors controlling the activity of the Proventriculus, bees were injected with either metabolizable or non-metabolizable carbohydrates. Only the injection of metabolizable carbohydrates modulated the activity of the Proventriculus, indicating that the titers of metabolizable carbohydrates are involved in the feedback loop controlling crop emptying, and that haemolymph osmolality alone does not influence the activity of the Proventriculus.
Hiroyuki Kaiya - One of the best experts on this subject based on the ideXlab platform.
-
Correlation of ghrelin concentration and ghrelin, ghrelin-O-acetyltransferase (GOAT) and growth hormone secretagogue receptor 1a mRNAs expression in the Proventriculus and brain of the growing chicken
Peptides, 2014Co-Authors: Takio Kitazawa, Takeo Hiraga, Hiroki Teraoka, Noriko Yaosaka, Hiroyuki KaiyaAbstract:Abstract To determine mechanisms for age-related decrease of GHS-R1a expression in the chicken Proventriculus, changes in mRNA expression of ghrelin and ghrelin-O-acetyltransferase (GOAT) as well as ghrelin concentrations in the Proventriculus and plasma were examined in growing chickens. Changes in expression levels of ghrelin , GOAT and GHS-R1a mRNAs were also examined in different brain regions (pituitary, hypothalamus, thalamus, cerebellum, cerebral cortex, olfactory bulb, midbrain and medulla oblongata). Ghrelin concentrations in the Proventriculus and plasma increased with aging and reached plateaus at 30–50 days after hatching. High level of ghrelin mRNA decreased at 3 days after hatching, and it became stable at half of the initial level. Expression levels of GHS-R1a and GOAT decreased 3 or 5 days after hatching and became stable at low levels. Significant negative correlations were found between plasma ghrelin and mRNA levels of GOAT and GHS-R1a . Expression levels of ghrelin mRNA were different in the brain regions, but a significant change was not seen with aging. GHS-R1a expression was detected in all brain regions, and age-dependent changes were observed in the pituitary and cerebellum. Different from the Proventriculus, the expression of GOAT in the brain increased or did not change with aging. These results suggest that decreased GHS-R1a and GOAT mRNA expression in the Proventriculus is due to endogenous ghrelin-induced down-regulation. Expression levels of ghrelin , GOAT and GHS-R1a in the brain were independently regulated from that in the Proventriculus, and age-related and region-dependent regulation pattern suggests a local effect of ghrelin system in chicken brain.
-
Changes in ghrelin levels of plasma and Proventriculus and ghrelin mRNA of Proventriculus in fasted and refed layer chicks
Domestic animal endocrinology, 2006Co-Authors: Hiroyuki Kaiya, Ei-suke Saito, Tetsuya Tachibana, Mitsuhiro Furuse, Kenji KangawaAbstract:This is a test-report of ghrelin levels in plasma and Proventriculus, the glandular portion of the avian stomach, by using a specific radioimmunoassay for acylated ghrelin, as well as the expression of the ghrelin gene in the Proventriculus after a 12-h fasting period followed by a 6-h feeding period with 6-day-old layer chicks. After fasting, the plasma ghrelin levels increased from 21.3 ± 4.5 to 32.9 ± 5.0 fmol/ml, but once refed it returned to the control value. After fasting, the ghrelin mRNA and the peptide levels in the Proventriculus increased, and ghrelin mRNA levels remained high but once refed the ghrelin content returned to the control level. Furthermore, in order to examine the effect of increased circulating ghrelin on food intake, a bolus intravenous injection of 500 pmol of chicken ghrelin was given to 8-day-old chicks. The ghrelin injection did not cause any significant changes in food intake. These results indicate that the levels of ghrelin and its mRNA with layer chicks are altered according to the feeding state and this in a similar manner as has been observed in mammals. Unlike in mammals, an increase in circulating ghrelin does not cause the promotion of food intake in chicks.
-
Exogenous administration of octanoic acid accelerates octanoylated ghrelin production in the Proventriculus of neonatal chicks.
Biochemical and biophysical research communications, 2005Co-Authors: Maya Yamato, Hiroyuki Kaiya, Reiko Wada, Ichiro Sakata, Takafumi SakaiAbstract:Ghrelin is modified by fatty acid at the third serine residue. In this study, derivation of fatty acid for acylation of ghrelin was investigated using a hatchling chicken model. We first studied ghrelin gene expression and production in the neonatal chick Proventriculus and then investigated the effect of exogenous octanoic acid (OA) administration on acylated ghrelin production. In a free-feeding condition on day 2.5 after hatching, the density of ghrelin mRNA-expressing (ghrelin-ex) cells was greater than that of ghrelin-immunopositive (ghrelin-ip) cells, but no difference was found between those densities in adult chickens. Intraperitoneal or oral administration of OA for a few days significantly increased the density of ghrelin-ip cells without any changes in ghrelin-ex cells and elevated only octanoylated ghrelin levels in the Proventriculus. The results indicate that fatty acid absorbed from food is directly utilized in acylated ghrelin production in the chicken.
-
Existence of ghrelin-immunopositive and -expressing cells in the Proventriculus of the hatching and adult chicken.
Regulatory peptides, 2003Co-Authors: Reiko Wada, Hiroyuki Kaiya, Ichiro Sakata, Kazuaki Nakamura, Yujiro Hayashi, Kenji Kangawa, Takafumi SakaiAbstract:Ghrelin was isolated from the rat stomach as an endogenous ligand for the growth hormone secretagogue receptor (GHS-R) and has been found in the gastrointestinal tract of many vertebrates. Although the sequence and structure of chicken ghrelin has recently been determined, morphological characteristics of ghrelin cells in the chicken gastrointestinal tract are still obscure. In this study, we investigated ghrelin expression and distribution of ghrelin-producing cells in the hatching and adult chicken gastrointestinal tract by RT-PCR, immunohistochemistry and in situ hybridization. Ghrelin mRNA expression was observed mainly in the Proventriculus in the hatching chicken and in the Proventriculus, pylorus and duodenum of the adult chicken by RT-PCR. Ghrelin-immunopositive (ghrelin-ip) cells in the Proventriculus were located at the mucosal layer but not in the myenteric plexus or smooth muscle layer. The number of ghrelin-ip cells in the adult chicken was greater than that in the hatching chicken. Interestingly, in the adult chicken, the number of ghrelin-ip cells were almost the same as that of ghrelin mRNA-expressing (ghrelin-ex) cells; however, in the hatching chicken, the number of ghrelin-ex cells was greater than that of ghrelin-ip cells. These results clearly demonstrate that ghrelin-producing cells exist in the chicken gastrointestinal tract, especially in the Proventriculus, from hatching to adult stages of development, as well as in mammals.
Mark P. Richards - One of the best experts on this subject based on the ideXlab platform.
-
Communication in Genomics and Proteomics Characterization of turkey and chicken ghrelin genes, and regulation of ghrelin and ghrelin receptor mRNA levels in broiler chickens
2006Co-Authors: Mark P. Richards, Stephen M. Poch, John P. McmurtryAbstract:Ghrelin, a peptide hormone produced by the stomach in mammals, stimulates growth hormone release and food intake. Recently, ghrelin was identiWed and characterized in chicken Proventriculus and shown to stimulate growth hormone release but inhibit feed intake. The purpose of this work was to identify and further characterize the ghrelin gene in chickens and in turkeys. Using molecular cloning techniques we have sequenced cDNAs corresponding to chicken (White Leghorn) and turkey ghrelin mRNAs. A total of 844 (chicken) or 869 (turkey) bases including the complete coding regions (CDS), and the 5- and 3-untranslated regions (UTRs) were determined. Nucleotide sequence (CDS) predicted a 116 amino acid precursor protein (preproghrelin) for both the chicken and the turkey that demonstrated complete conservation of an N-terminal ‘active core’ (GSSF) including a serine (position 3 of the mature hormone) known to be a modiWcation (acylation) site important for ghrelin bioactivity. Additional nucleotide sequence was found in the 5-UTRs of both Leghorn and turkey cDNAs that was not present in broilers or the red jungle fowl. The turkey ghrelin gene, sequenced from genomic DNA templates, contained Wve exons and four introns, a structure similar to mammalian and chicken ghrelin genes. Ghrelin was highly expressed in Proventriculus with much lower levels of expression in other tissues such as pancreas, brain, and intestine. RT-PCR was used to quantify ghrelin mRNA levels relative to 18S rRNA in 3-week-old male broiler chickens. The level of ghrelin mRNA increased in Proventriculus in response to fasting but did not decline with subsequent refeeding. Plasma ghrelin levels did not change signiWcantly in response to fasting or refeeding and did not appear to reXect changes in Proventriculus ghrelin mRNA levels. Ghrelin mRNA levels declined in broiler pancreas after a 48 h fast and increased upon refeeding. Expression of the gene encoding the receptor for ghrelin (growth hormone secretagogue receptor, GHS-R) and a variant form was detected in a variety of tissues collected from 3-week-old male broiler chickens possibly suggesting autocrine/paracrine eVects. These results oVer new information about the avian ghrelin and ghrelin receptor genes and the potential role that this system might play in regulating feed intake and energy balance in poultry. Published by Elsevier Inc.
-
Characterization of turkey and chicken ghrelin genes, and regulation of ghrelin and ghrelin receptor mRNA levels in broiler chickens.
General and comparative endocrinology, 2005Co-Authors: Mark P. Richards, Stephen M. Poch, John P. McmurtryAbstract:Ghrelin, a peptide hormone produced by the stomach in mammals, stimulates growth hormone release and food intake. Recently, ghrelin was identified and characterized in chicken Proventriculus and shown to stimulate growth hormone release but inhibit feed intake. The purpose of this work was to identify and further characterize the ghrelin gene in chickens and in turkeys. Using molecular cloning techniques we have sequenced cDNAs corresponding to chicken (White Leghorn) and turkey ghrelin mRNAs. A total of 844 (chicken) or 869 (turkey) bases including the complete coding regions (CDS), and the 5'- and 3'-untranslated regions (UTRs) were determined. Nucleotide sequence (CDS) predicted a 116 amino acid precursor protein (preproghrelin) for both the chicken and the turkey that demonstrated complete conservation of an N-terminal 'active core' (GSSF) including a serine (position 3 of the mature hormone) known to be a modification (acylation) site important for ghrelin bioactivity. Additional nucleotide sequence was found in the 5'-UTRs of both Leghorn and turkey cDNAs that was not present in broilers or the red jungle fowl. The turkey ghrelin gene, sequenced from genomic DNA templates, contained five exons and four introns, a structure similar to mammalian and chicken ghrelin genes. Ghrelin was highly expressed in Proventriculus with much lower levels of expression in other tissues such as pancreas, brain, and intestine. RT-PCR was used to quantify ghrelin mRNA levels relative to 18S rRNA in 3-week-old male broiler chickens. The level of ghrelin mRNA increased in Proventriculus in response to fasting but did not decline with subsequent refeeding. Plasma ghrelin levels did not change significantly in response to fasting or refeeding and did not appear to reflect changes in Proventriculus ghrelin mRNA levels. Ghrelin mRNA levels declined in broiler pancreas after a 48 h fast and increased upon refeeding. Expression of the gene encoding the receptor for ghrelin (growth hormone secretagogue receptor, GHS-R) and a variant form was detected in a variety of tissues collected from 3-week-old male broiler chickens possibly suggesting autocrine/paracrine effects. These results offer new information about the avian ghrelin and ghrelin receptor genes and the potential role that this system might play in regulating feed intake and energy balance in poultry.
