[Show abstract][Hide abstract] ABSTRACT: The effect of the aging on the activities of enzymes involved in UMP-CMP metabolism were evaluated in the heart of newborn (1-day-old), young (20-day-old), adult (12-month-old), and aged (30-month-old) chickens. In newborn animals, UMP metabolism proceeds preferentially towards cytidine compounds rather than to breakdown. In addition, two pathways different from those involved in de novo synthesis may contribute to the synthesis of UMP: one, through cytosine deaminase that shows its maximal activity; the other, by uridine kinase, the main "salvage" enzyme of pyrimidine nucleotides. In young chickens, pyrimidine metabolism regards especially UMP. In fact, the lower activities of cytidylate phosphatase and cytosine deaminase, together with the remarkable increase of uridine kinase indicate that the metabolic flux converges on the main salvage pathway. In adult chickens, pyrimidine catabolism is enhanced, as supported by the maximal activity of the enzymes involved in UMP-CMP breakdown. On the contrary, the remarkable reduction of the anabolic enzymes suggests a limited resort to the salvage pathways. Finally, in aged chickens a reduced pyrimidine catabolism and a greater utilization of the salvage pathways appear to take place, thus contributing to the maintenance of pyrimidine nucleotide pool.
Preview · Article · Jan 1999 · Biochemistry and molecular biology international
[Show abstract][Hide abstract] ABSTRACT: The activities of enzymes involved in GMP metabolism were studied in the heart of aging chickens. In newborn (1-day-old) animals, GMP breakdown apparently leads to the final products of purine metabolism, as the activity of hypoxanthine-guanine phosphoribosyl-transferase (HGPRT), the salvage enzyme of GMP is not detectable. On the contrary, HGPRT shows maximal activity in young (20-day-old) chickens, when xanthine oxidase activity is very low, indicating that the metabolic flux converges on the salvage pathway. Again, maximal activity of the catabolic enzymes and a limited resort to the salvage pathway characterize GMP metabolism of adult (12-month-old) hearts. Finally, in aged (30-month-old) chickens, a reduced GMP catabolism and a greater utilization of the salvage pathway might contribute to the maintenance of the guanine nucleotide pool. In conclusion, the pattern of the activities of enzymes relating to GMP metabolism in the aging heart, compared to AMP metabolism, indicates a parallel temporal regulation of the purine pathways.
No preview · Article · Jan 1997 · Aging (Milan, Italy)
[Show abstract][Hide abstract] ABSTRACT: The activities of enzymes involved in adenine nucleotide metabolism and the concentration of their metabolic products were studied in the hearts of chickens from birth to advanced age. In particular, in order to investigate the main mechanisms which contribute to ensure availability of adenine nucleotides during ageing of the heart, IMP concentration and the activities of enzymes involved in its turnover were studied. In newborn animals, AMP degradation, though limited in amount, was found to lead to the final products of purine metabolism. In fact, the activity of hypoxanthine phosphoribosyl-transferase (HPRT)-the salvage enzyme of IMP-was not detected. On the contrary, in young chickens, the low concentration of final products of purine metabolism, together with a remarkable activity of HPRT and a high concentration of IMP, indicates that metabolic flux converges on the salvage pathway. In adult chickens, an increase of purine catabolism was observed. This, together with an optimal concentration of endogenous adenine nucleotides, is indicative of a particularly high AMP metabolism. Finally, in chickens of advanced age, a reduced purine catabolism appeared to take place, thus contributing to the maintenance of the adenine nucleotide pool. In ageing heart, a major role of IMP turnover probably consists in the preservation of adenine nucleotides and in the recovery of high-energy phosphates.
No preview · Article · Jul 1996 · Comparative biochemistry and physiology. Part A, Physiology
[Show abstract][Hide abstract] ABSTRACT: The qualitative and quantitative pattern of GAGs was examined by electrophoresis in aging chicken brain in four different stages starting from day 1 to 30 months. GAG content referred to defatted dry tissue exhibits constant decrease. Four main GAGs have been identified with a mobility corresponding to hyaluronate, condroitin sulfate, heparan sulfate and dermatan sulfate controls. Hyaluronate appears the main GAG represented while dermatan sulfate the minor one. Our data show that in chicken brain GAG percentage undergoes age-related changes.
No preview · Article · Jan 1996 · Bollettino della Società italiana di biologia sperimentale
[Show abstract][Hide abstract] ABSTRACT: The activity of adenylate deaminase, adenylate phosphatase and adenosine deaminase, as well as the endogenous content of adenine nucleotides, was examined in the heart of ageing chickens. In new-born (1-day-old) and young (20-day-old) chickens, AMP degradation in the heart seems to proceed preferentially through deamination, while in adult (1-year-old) through dephosphorylation. Compared with the adult heart, a 2-year-old one exhibits a decline of AMP catabolism. The total adenine nucleotide content and the concentration of ATP are higher in adult and aged chicken hearts, than in new-born and young ones. Adaptive mechanisms might occur in the heart of ageing chickens to ensure an adequate availability of adenine nucleotides.
No preview · Article · Feb 1995 · Comparative biochemistry and physiology. Part A, Physiology
[Show abstract][Hide abstract] ABSTRACT: The pattern of cytidylate and uridylate phosphatase, uridine phosphorylase, cytidine and cytosine deaminase activities has been studied in M. complexus during chick development. The comparison of these enzyme activities with thigh muscles ones has shown that quantitative and temporal changes occur, in parallel with the unusual pre-natal and early post-natal development of M. complexus. The results suggest that during the first period of incubation, UMP might follow the anabolic pathway UMP-UTP, which leads to cytidine nucleotides, while approaching the hatching, the catabolic pathway should prevail. In addition, immediately after hatching, pyrimidine metabolism is especially supported by cytidine nucleotides.
No preview · Article · Jan 1991 · Archivio italiano di anatomia e di embriologia. Italian journal of anatomy and embryology
[Show abstract][Hide abstract] ABSTRACT: GAGs content was examined in chick embryo brain starting from the 9th day of incubation to the 4th post-hatching day. Chondroitin 6-sulfate, hyaluronate and heparan sulfate were recovered at any developmental stage examined. C6-S was the main GAG (except on the 15th day), while HS was the least represented. The highest differences in the relative amounts of GAGs are observed on the 9th day. C6-S shows high developmental relative changes, while HA and HS exhibit a similar pattern.
No preview · Article · Aug 1990 · Bollettino della Società italiana di biologia sperimentale
[Show abstract][Hide abstract] ABSTRACT: The pattern of uridylate phosphatase and uridine phosphorylase has been studied in the liver, brain, heart and thigh muscles of the chick during development. The study of enzymes involved in pyrimidine metabolism confirms that differences in utilisation of the metabolic pathways exist during ontogenesis. In the liver, starting from the 12th day, an active metabolic pathway, leading to UMP via cytosine should be added to the catabolic ones. In the brain, the second period of embryogenesis should be characterized by a lower utilisation of the catabolic pathways and by an increase of the anabolic ones. In the heart, pyrimidine metabolism during development regards especially UMP. In skeletal muscle, pyrimidine metabolism shows low activity.
No preview · Article · Jan 1990 · The Italian journal of biochemistry
[Show abstract][Hide abstract] ABSTRACT: Sugar content was examined in soluble and insoluble glycoproteins extracted from the chick embryo brain at different developmental stages. The content of hexosamines and uronic acids in the soluble fraction is higher during the whole period examined. The difference between the two fractions reaches a maximum at the 15th day. The insoluble fraction shows the highest content of sialic acid and fucose in comparison with the soluble one, especially toward hatching. The sialic acid/fucose ratio shows a different pattern in the two fractions examined, particularly in the soluble glycoproteins. The patterns of sialic acid and fucose indicate that quantitative and qualitative developmental changes occur in the soluble and insoluble glycoproteins. All sugars examined show significant changes on the 15th day, suggesting that this stage may represent a critical period in the development of the chick embryo brain.
No preview · Article · Nov 1989 · Bollettino della Società italiana di biologia sperimentale
[Show abstract][Hide abstract] ABSTRACT: The pattern of cytidylate phosphatase, cytidine and cytosine deaminase has been studied in brain, liver, heart and thigh muscles during chick development. The enzymes involved in CMP catabolism appear in the tissues examined at different developmental periods. In the brain and heart a "salvage pathway" would appear in the pyrimidine metabolism earlier than in the purine one. An attempt has been made to explain the probable physiological role, in relation to differentiation, of the metabolic pathways observed in the tissues examined.
No preview · Article · Feb 1983 · Comparative Biochemistry and Physiology Part C Comparative Pharmacology and Toxicology
[Show abstract][Hide abstract] ABSTRACT: 1.1. The pattern of guanylate phosphatase, guanosine phosphorylase, guanine deaminase and xanthine oxidase has been studied in chick embryo liver, heart and thigh muscles.2.2. During the first period of incubation GMP breakdown led to the end products of purine degradation; on the 15th day in the liver and on the 18th day in the heart, guanosine phosphorylase would play an “anabolic” rather than “catabolic” role, being involved in a salvage pathway for the biosynthesis of purine nucleotides.3.3. The temporal regulation of AMP and GMP metabolic pathways would follow a parallel evolution in liver and in heart but a different one in thigh muscles.
No preview · Article · Dec 1980 · Comparative biochemistry and physiology. B, Comparative biochemistry
[Show abstract][Hide abstract] ABSTRACT: Glycosaminoglycans extracted by CPC precipitation from chick embryo skin at 9, 12, 15, 18, 21 days of incubation were separated by three different electrophoretic methods on acetate cellulose strips. We observed the presence of Hyaluronic acid, Dermatan Sulfate and Chondroitin-4-Sulfate during the whole period considered and of Heparan Sulfate only after the 9th day. Dermatan Sulfate increases until the 15th day then decreases progressively; on the contrary Hyaluronic acid and Chondroitin-4-Sulfate decrease during days 9 to 15 then increase until hatching. Heparan Sulfate appear the 9th day then increases progressively until hatching.
No preview · Article · Mar 1980 · Bollettino della Società italiana di biologia sperimentale
[Show abstract][Hide abstract] ABSTRACT: Polyanionic glycans extracted from Euglena gracilis have been studied by biochemical, chromatographic and electrophoretic analysis. Our results show the presence of a fraction which precipitate with CPC and another one which not precipitate with CPC. The CPC precipitable material fractionated on CPC-Cellulose column shows the presence of 5 Glycosaminoglycans; the not CPC precipitable material contains uronic acid, galactose, sulfate, galactosamine and cannot be related to Keratan sulfate.
No preview · Article · Oct 1979 · Bollettino della Società italiana di biologia sperimentale
[Show abstract][Hide abstract] ABSTRACT: The developmental patterns of enzyme activities related to GMP metabolism have been investigated in chick embryo musculus complexus (m. Complexus). Guanylate phosphatase activity increases conspicuously from 18th to 21st day, guanosine phosphorylase increases on the 21st day and the guanase shows a very low activity during the whole period considered. Xanthine oxidase was always found absent. The results suggest that during the first period of incubation GMP breakdown in chick embryo m. complexus might follow a catabolic pathway, while starting from the 18th day some guanine might be converted to GMP originating a new metabolic pathway as previously suggested for AMP metabolism.
No preview · Article · Oct 1979 · Bollettino della Società italiana di biologia sperimentale
[Show abstract][Hide abstract] ABSTRACT: 1. This paper describes the changes in the activity of adenylate deaminase, adenylate and inosinate phosphatase, and adenosine deaminase in the developing chick embryo liver. 2. The adenylate and inosinate phosphatase and adenosine deaminase activity appears considerably higher in chick embryo liver with respect to other chick embryo tissues previously examined. 3. During development the control exerted by ATP on AMP breakdown undergoes variations. Consequently, in the first period of incubation AMP is degraded by the direct pathway (AMP-IMP) and in the last period of incubation by the indirect pathway (AMP-adenosine). In the intermediate period (from the 12th to the 15th day of incubation) both pathways may be followed. 4. The ability to synthesize purine nucleotides through "salvage pathway" seems to be acquired by embryonic liver at least at the 15th day.
No preview · Article · Feb 1978 · Comparative biochemistry and physiology. B, Comparative biochemistry
[Show abstract][Hide abstract] ABSTRACT: 1.1. The pattern of adenylate deaminase, adenylate and inosinate phosphatase and adenosine deaminase has been studied in chick embryo heart, m. complexus and thigh muscles at various developmental stages.2.2. The regulation of AMP deaminase and 5′-nucleotidases by ATP occurs in different ways in the muscles examined.3.3. Adenosine deaminase can be detected in the heart and in thigh muscles starting from the 18th day.4.4. During the first period of incubation the AMP breakdown might follow the “direct pathway” (AMP-IMP).5.5. The ability to synthesize purine nucleotides through “salvage pathway” is not acquired by chick embryo before the 18th day.
No preview · Article · Jan 1978 · Comparative biochemistry and physiology. B, Comparative biochemistry