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Michael J Conlon - One of the best experts on this subject based on the ideXlab platform.

  • the alyteserins two families of antimicrobial peptides from the skin secretions of the midwife toad alytes obstetricans alytidae
    Peptides, 2009
    Co-Authors: Michael J Conlon, Anni Demandt, Hubert Vaudry, Jérôme Leprince, Per F Nielsen, Douglas C. Woodhams
    Abstract:

    Abstract Two families of structurally related C-terminally α-amidated antimicrobial peptides have been identified in norepinephrine-stimulated skin secretions of the midwife toad Alytes obstetricans (Alytidae). The alyteserin-1 peptides (Gly-Leu-Lys-(Asp/Glu)-Ile-Phe-Lys-Ala-Gly-Leu-Gly-Ser-Leu-Val-Lys-(Gly/Asn)-Ile-Ala-Ala-His-Val-Ala-(Asn/Ser).NH 2 ) show limited structural similarity to the ascaphins from the skins of frogs of the family Leiopelmatidae. Alyteserin-2a (Ile-Leu-Gly-Lys-Leu-Leu-Ser-Thr-Ala-Ala-Gly-Leu-Leu-Ser-Asn-Leu.NH 2 ) and alyteserin-2b and -2c (Ile-Leu-Gly-Ala-Ile-Leu-Pro-Leu-Val-Ser-Gly-Leu-Leu-Ser-(Asn/Ser)-Lys-Leu.NH 2 ) show limited sequence identity with bombinin H6, present in the skins of frogs of the family Bombinatoridae. The alyteserin-1 peptides show selective growth inhibitory activity against the Gram-negative bacteria Escherichia coli (MIC = 25 μM) whereas alyteserin-2a is more potent against the Gram-positive bacteria Staphylococcus aureus (MIC = 50 μM). The hemolytic activity against human erythrocytes of all peptides tested is relatively weak (LC 50  > 100 μM). The data demonstrate that the frogs belonging to the family Alytidae are among those producing dermal antimicrobial peptides that may represent a component of the animal's system of innate immunity.

  • evidence for processing enzymes in the abdominal gland of the newt cynops pyrrhogaster that generate sodefrin from its biosynthetic precursor
    Zoological Science, 2007
    Co-Authors: Tomoaki Nakada, Michael J Conlon, Fumiyo Toyoda, Yoko Ishizuka, Takeo Iwata, Takashi Kato, Sakae Kikuyama
    Abstract:

    Sodefrin (Ser-Ile-Pro-Ser-Lys-Asp-Ala-Leu-Leu-Lys) is a female-attracting peptide pheromone secreted by the abdominal gland of the male red-bellied newt, Cynops pyrrhogaster. Sequence analysis of a cDNA encoding sodefrin revealed that the peptide is located in the C-terminal region of its precursor protein (residues 177-186 of preprosodefrin) and extended from its C-terminus by the tripeptide sequence Ile(187)-Ser(188)-Ala(189) and flanked at its N-terminus by Leu(174)-Gly(175)-Arg(176). This suggests that sodefrin is generated by enzymatic cleavage at monobasic (Lys and Arg) sites within the precursor molecule. To demonstrate the presence in the abdominal gland of proteolytic enzymes capable of generating sodefrin, an enzymatic assay was developed using t-butoxycarbo-nyl (Boc)-Leu-Gly-Arg-4methylcoumaryl-7-amide (MCA) and Boc-Leu-Leu-Lys-MCA as synthetic substrates. A crude extract of the abdominal gland hydrolyzed both substrates to liberate 7-amino-4- methylcoumarin, suggesting that enzymes that generate sodefrin from its precursor molecule are present in the gland. The activity in the extract for cleaving Boc-Leu-Gly-Arg-MCA was optimal at pH 9.0 and 45 degrees C and for Boc-Leu-Leu-Lys-MCA at pH 9.0 and 40 degrees C. The effects of a range of specific inhibitors on activities in the extract suggest an involvement of enzymes belonging to the serine protease family. It was also demonstrated that enzymatic activity in an extract of the abdominal glands of sexually developed males was significantly (three- to six-fold; p<0.01) higher than that of sexually undeveloped males.

  • purification and characterization of islet hormones insulin glucagon pancreatic polypeptide and somatostatin from the burmese python python molurus
    Regulatory Peptides, 1997
    Co-Authors: Michael J Conlon, Stephen M. Secor, Dennis C. Mynarcik, Thomas E Adrian, Jonathan Whittaker
    Abstract:

    Insulin was purified from an extract of the pancreas of the Burmese python, Python molurus (Squamata:Serpentes) and its primary 10 20 structure established as: A Chain: Gly-Ile-Val-Glu-Gln-Cys-Cys-Glu-Asn-Thr -Cys-Ser-Leu-Tyr-Glu-Leu-Glu-Asn-Tyr-Cys -Asn. B- 10 20 Chain: Ala-Pro-Asn-Gln-His-Leu-Cys-Gly-Ser-His -Leu-Val-Glu-Ala-Leu-Tyr-Leu-Val-Cys-Gly -Asp-Arg-Gly-Phe-Tyr-Tyr-Ser-Pro- 30 Arg-Ser . With the exception of the conservative substitution Phe → Tyr at position B25, those residues in human insulin that comprise the receptor-binding and those residues involved in dimer and hexamer formation are fully conserved in python insulin. Python insulin 125 was slightly more potent (1.8-fold) than human insulin in inhibiting the binding of (( I-Tyr-A14) insulin to the soluble full-length recombinant human insulin receptor but was slightly less potent (1.5-fold) than human insulin for inhibiting binding to the secreted 28 extracellular domain of the receptor. The primary structure of python glucagon contains only one amino acid substitution (Ser → Asn) compared with turtle / duck glucagon and python somatostatin is identical to that of mammalian somatostatin-14. In contrast, python 10 20 pancreatic polypeptide (Arg-Ile-Ala-Pro-Val-Phe-Pro-Gly-Lys-Asp -Ala-Ser-Val-Asp-Glu-Leu-Ala-Lys-Phe-Tyr -Thr-Glu-Leu-Gln-Gln- 30 Tyr-Leu-Asn-Ser-Ile -Asn-Arg-Pro-Arg-Phe.NH ) contains only 35 instead of the customary 36 residues and the amino acid sequence 2 of this peptide has been poorly conserved between reptiles and birds (18 substitutions compared with alligator and 20 substitutions compared with chicken). © 1997 Elsevier Science B.V.

  • multiple bradykinin related peptides from the skin of the frog rana temporaria
    Peptides, 1997
    Co-Authors: Michael J Conlon, Ulrika Aronsson
    Abstract:

    Abstract Conlon, J. M. and U. Aronsson. Multiple bradykinin-related peptides from the skin of the Frog, Rana temporaria. Peptides 18(3) 361–365, 1997.—The skin of the European common frog, Rana temporaria, contains a very high concentration of bradykinin (BK) but the mode of biosynthesis of the peptide is unknown. In addition to BK, we have isolated from an extract of R. temporaria skin the metabolites [des-Arg 9 ]BK and [hydroxyprolyl 3 ]BK. Peptides were also isolated that represent partially processed intermediates in the biosynthetic pathway to BK and comprise BK extended from its N -terminus by -Gly-Val-Ile-Pro-Leu-Leu and three peptides comprising BK extended from its C -terminus by -Ile-Ala, by -Ile-Ala-Pro-Ala-Ser-Thr-Leu, and by -Ile-Ala-Pro-Ala-Ser-Ile-Leu. The isolation of two C -terminally extended BK-containing peptides differing by a single amino substitution indicates that the biosynthetic precursor of frog skin BK may contain more than one copy of the BK sequence and/or more than one gene encoding BK is expressed. The structures of the biosynthetic intermediates suggest that BK in frog skin is generated by the action of cellular endoproteinase(s) cleaving at the site of monobasic residues rather than by the action of the kallikrein-kinin system.

  • tachykinins substance p neurokinin a and neuropeptide γ and neurotensin from the intestine of the burmese python python molurus
    Peptides, 1997
    Co-Authors: Michael J Conlon, Thomas E Adrian, Stephen M. Secor
    Abstract:

    Abstract Conlon, J. M., T. E. Adrian and S. M. Secor. Tachykinins (substance P, neurokinin A and neuropeptide γ,) and neurotensin from the intestine of the burmese python, Python molurus. Peptides 18(10) 1505–1510, 1997.—Peptides with substance P-like immunoreactivity, neurokinin A-like immunoreactivity and neurotensin-like immunoreactivity were isolated in pure form from an extract of the intestine of the Burmese python ( Python molurus ). The primary structure of python substance P (Arg-Pro-Arg-Pro-Gln-Gln-Phe-Tyr-Gly-Leu-Met-NH 2 ) shows one amino acid substitution (Phe 8 → Tyr) compared with chicken/alligator substance P and an additional substitution (Lys 3 → Arg) as compared with mammalian substance P. The neurokinin A-like immunoreactivity was separated into two components. Python neuropeptide γ (Asp-Ala-Gly-Tyr-Ser-Pro-Leu-Ser-His-Lys-Arg-His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met-NH 2 shows three substitutions (Gly 5 → Ser, Gln 6 → Pro and Ile 7 → Leu) compared with alligator neuropeptide γ and an additional substitution (His 4 → Tyr) compared with mammalian neuropeptide γ. Python neurokinin A (His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met.NH 2 ) is identical to human/chicken/alligator neurokinin A. Python neurotensin (pGlu-Leu-Val-His-Asn-Lys-Ala-Arg-Pro-Tyr-Ile-Leu) is identical to chicken/alligator neurotensin. The data are indicative of differential evolutionary pressure to conserve the amino acid sequences of reptilian gastrointestinal peptides.

Delbert M Gatlin - One of the best experts on this subject based on the ideXlab platform.

  • imbalanced dietary levels of branched chain amino acids affect growth performance and amino acid utilization of juvenile red drum sciaenops ocellatus
    Aquaculture, 2018
    Co-Authors: Sergio Castillo, Delbert M Gatlin
    Abstract:

    Abstract Imbalanced dietary levels of branched-chain amino acids (BCAAs) are known to produce antagonistic effects in pigs, rats and humans, affecting the concentration of BCAAs in plasma and ultimately depressing growth. In fish, antagonism involving BCAAs has not been fully characterized or understood. The objective of this study was to determine the effects of imbalanced dietary levels of BCAAs on growth performance and amino acid utilization of juvenile red drum. A control diet was prepared by combining lyophilized red drum muscle and crystalline amino acids, while keeping leucine (Leu), isoleucine (Ile) and valine (Val) at the previously quantified minimum dietary requirement levels for red drum. Six experimental diets were prepared by supplementing the control diet with (1) an excess of Leu, (2) an excess of Ile, (3) an excess of Val, (4) an excess of Leu and Ile, (5) an excess of Ile and Val, and (6) an excess of Leu and Val. Red drum juveniles were stocked in 38-L glass aquaria, and diets were fed to fish in triplicate aquaria, twice daily, for 45 d. At the end of the feeding trial, growth performance was evaluated and postprandial levels of BCAAs in plasma were analyzed. Growth performance of red drum was significantly depressed by an excess of dietary Leu, but not by an excess of Ile nor Val. The postprandial concentration of plasma Leu, Ile or Val was significantly higher in fish fed an excess of Leu, Ile or Val, respectively. Postprandial levels of BCAAs in plasma did not indicate that an excess of Leu blocked the intestinal absorption or promoted the catabolism of Ile and/or Val in red drum, as has been reported in other species. However, excess Leu did significantly reduce the postprandial concentration of α-ketoglutarate in plasma, possibly indicating a higher ratio of transamination due to the imbalanced postprandial concentration of BCAAs in plasma. In conclusion, an antagonistic effect due to excess dietary Leu was confirmed in juvenile red drum. This study represents a step forward in understanding the nature of the antagonistic effects among BCAAs in fish.

  • dietary requirements for leucine isoleucine and valine branched chain amino acids by juvenile red drum sciaenops ocellatus
    Aquaculture Nutrition, 2018
    Co-Authors: Sergio Castillo, Delbert M Gatlin
    Abstract:

    The objective of this study was to determine the minimum dietary requirements of the branched-chain amino acids (BCAAs: leucine [Leu], isoleucine [Ile] and valine [Val]) for juvenile red drum, Sciaenops ocellatus. This was accomplished by conducting three independent 49-day feeding trials with juvenile red drum. Experimental diets were prepared by supplementing a basal diet containing 370 g/kg crude protein from red drum muscle and crystalline amino acids with incremental levels of Leu (9.0, 13.0, 17.0, 21.0, 25.0 and 29.0 g/kg of dry diet), Ile (5.0, 8.0, 11.0, 14.0, 17.0 and 20.0 g/kg of dry diet) and Val (6.8, 8.0, 9.2, 10.4, 11.6, 12.8 and 14.0 g/kg of dry diet). Fish were fed to apparent satiation twice daily in each trial, after which growth performance parameters were calculated and body composition and concentrations of BCAAs in plasma were analysed. Incremental levels of dietary Leu, Ile and Val significantly affected weight gain, feed efficiency and protein retention. Analyses of the weight gain data using a broken-line regression model estimated the minimum Leu, Ile and Val requirements for maximum growth of juvenile red drum to be 15.7 ± 1.7 g/kg (±95% confidence interval), 11.1 ± 2.3 g/kg and 12.4 ± 0.6 g/kg of dry diet, respectively.

Jan V. Nørgaard - One of the best experts on this subject based on the ideXlab platform.

  • Nontargeted LC–MS metabolomics approach for metabolic profiling of plasma and urine from pigs fed branched chain amino acids for maximum growth performance
    Journal of Proteome Research, 2016
    Co-Authors: Elham A. Soumeh, Mette S. Hedemann, Hanne D. Poulsen, Etienne Corrent, Jacob Van Milgen, Jan V. Nørgaard
    Abstract:

    The metabolic response in plasma and urine of pigs when feeding an optimum level of branched chain amino acids (BCAAs) for best growth performance is unknown. The objective of the current study was to identify the metabolic phenotype associated with the BCAAs intake level that could be linked to the animal growth performance. Three dose–response studies were carried out to collect blood and urine samples from pigs fed increasing levels of Ile, Val, or Leu followed by a nontargeted LC–MS approach to characterize the metabolic profile of biofluids when dietary BCAAs are optimum for animal growth. Results showed that concentrations of plasma hypoxanthine and tyrosine (Tyr) were higher while concentrations of glycocholic acid, tauroursodeoxycholic acid, and taurocholic acid were lower when the dietary Ile was optimum. Plasma 3-methyl-2-oxovaleric acid and creatine were lower when dietary Leu was optimum. The optimum dietary Leu resulted in increased urinary excretion of ascorbic acid and choline and relatively decreased excretion of 2-aminoadipic acid, acetyl-dl-valine, Ile, 2-methylbutyrylglycine, and Tyr. In conclusion, plasma glycocholic acid and taurocholic acid were discriminating metabolites to the optimum dietary Ile. The optimum dietary Leu was associated with reduced plasma creatine and urinary 2-aminoadipic acid and elevated urinary excretion of ascorbic acid and choline. The optimum dietary Val had a less pronounced metabolic response reflected in plasma or urine than other BCAA.

  • Nontargeted LC–MS Metabolomics Approach for Metabolic Profiling of Plasma and Urine from Pigs Fed Branched Chain Amino Acids for Maximum Growth Performance
    2016
    Co-Authors: Elham A. Soumeh, Mette S. Hedemann, Etienne Corrent, Jacob Van Milgen, Hanne D. Poulsen, Jan V. Nørgaard
    Abstract:

    The metabolic response in plasma and urine of pigs when feeding an optimum level of branched chain amino acids (BCAAs) for best growth performance is unknown. The objective of the current study was to identify the metabolic phenotype associated with the BCAAs intake level that could be linked to the animal growth performance. Three dose–response studies were carried out to collect blood and urine samples from pigs fed increasing levels of Ile, Val, or Leu followed by a nontargeted LC–MS approach to characterize the metabolic profile of biofluids when dietary BCAAs are optimum for animal growth. Results showed that concentrations of plasma hypoxanthine and tyrosine (Tyr) were higher while concentrations of glycocholic acid, tauroursodeoxycholic acid, and taurocholic acid were lower when the dietary Ile was optimum. Plasma 3-methyl-2-oxovaleric acid and creatine were lower when dietary Leu was optimum. The optimum dietary Leu resulted in increased urinary excretion of ascorbic acid and choline and relatively decreased excretion of 2-aminoadipic acid, acetyl-dl-valine, Ile, 2-methylbutyrylglycine, and Tyr. In conclusion, plasma glycocholic acid and taurocholic acid were discriminating metabolites to the optimum dietary Ile. The optimum dietary Leu was associated with reduced plasma creatine and urinary 2-aminoadipic acid and elevated urinary excretion of ascorbic acid and choline. The optimum dietary Val had a less pronounced metabolic response reflected in plasma or urine than other BCAA

Sergio Castillo - One of the best experts on this subject based on the ideXlab platform.

  • imbalanced dietary levels of branched chain amino acids affect growth performance and amino acid utilization of juvenile red drum sciaenops ocellatus
    Aquaculture, 2018
    Co-Authors: Sergio Castillo, Delbert M Gatlin
    Abstract:

    Abstract Imbalanced dietary levels of branched-chain amino acids (BCAAs) are known to produce antagonistic effects in pigs, rats and humans, affecting the concentration of BCAAs in plasma and ultimately depressing growth. In fish, antagonism involving BCAAs has not been fully characterized or understood. The objective of this study was to determine the effects of imbalanced dietary levels of BCAAs on growth performance and amino acid utilization of juvenile red drum. A control diet was prepared by combining lyophilized red drum muscle and crystalline amino acids, while keeping leucine (Leu), isoleucine (Ile) and valine (Val) at the previously quantified minimum dietary requirement levels for red drum. Six experimental diets were prepared by supplementing the control diet with (1) an excess of Leu, (2) an excess of Ile, (3) an excess of Val, (4) an excess of Leu and Ile, (5) an excess of Ile and Val, and (6) an excess of Leu and Val. Red drum juveniles were stocked in 38-L glass aquaria, and diets were fed to fish in triplicate aquaria, twice daily, for 45 d. At the end of the feeding trial, growth performance was evaluated and postprandial levels of BCAAs in plasma were analyzed. Growth performance of red drum was significantly depressed by an excess of dietary Leu, but not by an excess of Ile nor Val. The postprandial concentration of plasma Leu, Ile or Val was significantly higher in fish fed an excess of Leu, Ile or Val, respectively. Postprandial levels of BCAAs in plasma did not indicate that an excess of Leu blocked the intestinal absorption or promoted the catabolism of Ile and/or Val in red drum, as has been reported in other species. However, excess Leu did significantly reduce the postprandial concentration of α-ketoglutarate in plasma, possibly indicating a higher ratio of transamination due to the imbalanced postprandial concentration of BCAAs in plasma. In conclusion, an antagonistic effect due to excess dietary Leu was confirmed in juvenile red drum. This study represents a step forward in understanding the nature of the antagonistic effects among BCAAs in fish.

  • dietary requirements for leucine isoleucine and valine branched chain amino acids by juvenile red drum sciaenops ocellatus
    Aquaculture Nutrition, 2018
    Co-Authors: Sergio Castillo, Delbert M Gatlin
    Abstract:

    The objective of this study was to determine the minimum dietary requirements of the branched-chain amino acids (BCAAs: leucine [Leu], isoleucine [Ile] and valine [Val]) for juvenile red drum, Sciaenops ocellatus. This was accomplished by conducting three independent 49-day feeding trials with juvenile red drum. Experimental diets were prepared by supplementing a basal diet containing 370 g/kg crude protein from red drum muscle and crystalline amino acids with incremental levels of Leu (9.0, 13.0, 17.0, 21.0, 25.0 and 29.0 g/kg of dry diet), Ile (5.0, 8.0, 11.0, 14.0, 17.0 and 20.0 g/kg of dry diet) and Val (6.8, 8.0, 9.2, 10.4, 11.6, 12.8 and 14.0 g/kg of dry diet). Fish were fed to apparent satiation twice daily in each trial, after which growth performance parameters were calculated and body composition and concentrations of BCAAs in plasma were analysed. Incremental levels of dietary Leu, Ile and Val significantly affected weight gain, feed efficiency and protein retention. Analyses of the weight gain data using a broken-line regression model estimated the minimum Leu, Ile and Val requirements for maximum growth of juvenile red drum to be 15.7 ± 1.7 g/kg (±95% confidence interval), 11.1 ± 2.3 g/kg and 12.4 ± 0.6 g/kg of dry diet, respectively.

F X Roth - One of the best experts on this subject based on the ideXlab platform.

  • the effects of branched chain amino acid interactions on growth performance blood metabolites enzyme kinetics and transcriptomics in weaned pigs
    British Journal of Nutrition, 2010
    Co-Authors: Markus Wiltafsky, Michael W Pfaffl, F X Roth
    Abstract:

    The impact of excess dietary leucine (Leu) was studied in two growth assays with pigs (8-25 kg). In each trial, forty-eight pigs were allotted to one of six dietary groups. The dietary Leu supply increased from treatment L100 to L200 (three increments). To guarantee that interactions between the branched-chain amino acids (BCAA) were not cushioned either surpluses of isoleucine (Ile, expt 1) or valine (Val; expt 2) were avoided. In the fifth treatment, the effects of a simultaneous excess of Leu and Val (expt 1), or of Leu and Ile (expt 2) were investigated. The sixth treatment was a positive control. An increase in dietary Leu decreased growth performance, and increased plasma Leu and serum alpha-keto-isocaproate levels in a linear, dose-dependent manner. Levels of plasma Ile and Val, and of serum alpha-keto-beta-methylvalerate and alpha-keto-isovalerate, indicated increased catabolism. Linear increases in the activity of basal branched-chain alpha-keto acid dehydrogenase in the liver confirmed these findings. No major alterations occurred in the mRNA of branched-chain amino acid catabolism genes. In liver tissue from expt 2, however, the mRNA levels of growth hormone receptor, insulin-like growth factor acid labile subunit and insulin-like growth factor 1 decreased significantly with increasing dietary Leu. In conclusion, excess dietary Leu increased the catabolism of BCAA mainly through posttranscriptional mechanisms. The impact of excess Leu on the growth hormone--insulin-like growth factor-1 axis requires further investigation.