Plasma amino-acid concentrations during development in the rat

The plasma individual amino-acid concentrations in the rat during late foetal development and from the birth to the end of the weaning have been studied. Both the very low foetal amino-acid degrading capabilities in addition to the high amino-acid concentration ability of the placenta help to sustain considerably high plasma foetal amino-acid levels that favour considerably protein synthesis. There is a very important decrease in most amino-acid concentrations with birth, due to the cessation of placental transfer, relative immaturity of intake and assimilation processes and to the highly anabolic environment found in the pup. The changes in postnatal development plasma amino-acid patterns reflect directly the availability of amino acids in the diet, the maturation of the amino-acid metabolism pathways and transport systems and their use for protein synthesis (and other nitrogenous compounds). The main situation that affects individual amino-acid levels is the shift from high biological value milk protein to low biological value plant proteins in the rat chow pellets. The postnatal development is characterized by a high combined total amino-acids homeostasis with ample changes in individual amino-acid concentrations, that is maintained in spite of the deep changes in diet, size, metabolism, hormone environment, maturation, etc. observed in the rat from birth to weaning and adulthood.     

Patterns of amino acid enzyme in domestic fowl breast and leg muscle during development

Activities of alanine and aspartate transaminases, glutamine synthetase, adenylate deaminase, glutamate and xanthine dehydrogenases and lactate dehydrogenase were measured in leg and breast muscles of developing chicks from day 10 in ovo to day 5 of free life, and compared with measurements for adult hens. Xanthine dehydrogenase activity was low in both muscles with adult levels attained on day 15 in ovo. Glutamine synthetase for chicks was maintained higher during development than for adults in both muscles. Minor differences were observed between both muscles in all enzymes tested up to day 18. With low embryonic values and important rises before hatching, the differences were initiated in the posthatching period. Important differences were observed between adult levels of activity. Leg muscle revealed higher enzyme values except for lactate dehydrogenase and indistinguishable levels for adenylate deaminase and xanthine dehydrogenase in both muscles. Alanine, instead of glutamine, is postulated as the main nitrogen transport between muscle and liver in the domestic fowl.     

Changes in plasma glucose and lipid concentrations during treadmill exercise in domestic fowl

• 1.1. Plasma glucose, non-esterified fatty acid, triglyceride, cholesterol and lactate concentrations were measured during 90 min treadmill exercise at a work intensity of 55–60% maximum.
• 2.2. After 90 min exercise plasma glucose fell by 35% whilst the non-esterified fatty acid concentration rose to as much as 3–4 times resting.
• 3.3. Exercise had no significant effect on plasma cholesterol, triglyceride or lactate concentrations.
• 4.4. The findings indicate a progressive increase in fat utilization during prolonged exercise. Possible hormonal mechanisms underlying exercise-induced changes in lipid and carbohydrate metabolism are discussed.

     

Neuronal degeneration in the pineal ganglion during the post-hatching development of the domestic fowl

Summary The frequency of pineal ganglia associated with the pineal tract, and the numbers of acetylcholinesterasepositive neurons in these ganglia were studied in the domestic fowl during the post-hatching period by means of the acetylcholinesterase method. Furthermore, the degeneration of nerve cells in pineal ganglia of 40-day-old domestic fowl was investigated in detail at the electron-microscopic level. The rate of pineal organs containing one or more ganglia was 50% in 2- to 13-day-old, 38% in 40-day-old, and only 10% in 1-year-old domestic fowl. In parallel, the number of acetylcholinesterase-reactive nerve cells that constitute individual pineal ganglia decreased after hatching. Various degrees of neuronal degeneration were found in the pineal ganglia: swelling of the endoplasmic reticulum, electron-dense degeneration of the cytoplasm, and pyknosis of the nerve cell nucleus. Clusters of macrophages containing numerous lysosomes filled with debris-like material were scattered in the ganglion. In addition, plasma cells were observed in association with degenerating nerve cells. These results confirm the suggestion that the loss of acetylcholinesterase-positive nerve cells in the pineal ganglia of the domestic fowl is due to naturally occurring, programmed neuronal cell death. This process is discussed with reference to phenomena of cell death observed in other components of central nervous system.Fellow of the Alexander von Humboldt Foundation, Bonn, Federal Republic of GermanyThe authors are indebted to Professor A. Oksche and Dr. H.-W. Korf (Giessen) for stimulating discussions     

Somatostatin immunoneutralization affects plasma metabolite concentrations in the domestic fowl

Young leghorn cockerels were injected with antiserum to somatostatin (anti-SRIF) and plasma glucose, free fatty acids and alpha-amino nitrogen concentrations determined. Plasma glucose concentrations increased rapidly after anti-SRIF and remained high for up to 2 hr. Two different antisera tested had hyperglycaemic activity. Plasma free fatty acids also increased rapidly after administration of the two different anti-SRIFs, and remained high for about 1 hr. Plasma alpha-amino nitrogen increased during the first 30 min after anti-SRIF, then declined to levels significantly lower than control by 1-2 hr after injection. Anaesthesia reduced plasma concentrations of glucose and alpha-amino nitrogen, and also reduced the changes of these metabolites following anti-SRIF. The results show the importance of endogenous somatostatin in the regulation of plasma metabolite concentrations.     

Leptofibrils in intrafusal muscle fibres of muscle spindles in the domestic fowl

Summary Leptofibrils consisting of narrow dark and wide light bands at regular periods are commonly found in intrafusal muscle fibres of chicken muscle spindles. They are particularly abundant in intrafusal muscle fibres with the loose type of myofilaments. They occur either at the periphery of intrafusal muscle fibres or in deeper regions, or even close to sensory nerve terminals. Dark bands of some peripheral leptofibrils vary considerably in size and appear less regular in configuration. Lateral extensions from the dark bands may occur with or without interconnections. Lateral attachments to myofilaments at the immediate neighbourhood may also occur.     

Plasma atrial natriuretic factor concentrations and renal actions in the domestic fowl

Plasma atrial natriuretic factor concentrations in Rhode Island red hens averaged 72.1±6.9 pg·ml^-1, range 33.4–136.0 pg·ml^-1. The intravenous infusion of isotonic saline containing 3% dextran for 2 h produced no significant changes in plasma osmotic or electrolyte concentrations; however, haematocrit changes indicated vascular expansions of 14.4% after 1 h and 21.3% after 2 h and plasma atrial natriuretic factor concentrations were elevated by 190% and 257%, respectively. The intravenous infusion of chicken atrial natriuretic factor at rates of 10, 25, 50 and 100 ng·kg^-1·min^-1 for 20 min produced levels of plasma atrial natriuretic factor that were directly related to the infusion rate and which, in birds undergoing a steady-state diuresis/natriuresis driven by the intravenous infusion of isotonic saline at 1 ml·min^-1, produced dose-dependent increases of 19, 26, 38 and 55% in urine flow rate and of 8, 30, 49 and 77% in sodium excretion. Potassium excretion was significantly increased only at the two highest atrial natriuretic factor infusion rates. The observed correlation between plasma atrial natriuretic factor concentration and vascular volume together with the atrial natriuretic factor-induced modulation of renal salt and water elimination is consistent with the concept that in the chicken this peptide has a physiological role as a regulatory hormone in volume homeostasis.Abbreviations AII angiotensin II - ANF atrial natriuretic factor - AVT arginine vasotocin - BV blood volume - chANF chicken atrial natriuretic factor - CHE chicken heart extract - ECF extracellular fluid - EDTA ethylenediaminetetra-acetate - Hct haematocrit - i.v. intravenous - PCR plasma clearance rate - PRA plasma renin activity - RIA radioimmunoassay     

Expression of neuron-specific enolase in the pineal organ of the domestic fowl during post-hatching development

Immunohistochemistry for neuron-specific enolase (NSE) revealed that NSE is localized in both a limited number of pinealocytes and intrinsic afferent neurons in the pineal organ of the domestic fowl. Furthermore, a computer-assisted three-dimensional imaging technique allowed to clarify the reverse distributional pattern of both elements: NSE-positive pinealocytes displayed a dense distribution especially in the vesicular portion of the gland, whereas NSE-immunoreactive nerve cells were mainly found in the pineal stalk. The number of NSE-positive intrinsic neurons in the pineal organ of chickens decreased rapidly after hatching, with a concentration of these elements in the basal portion (stalk) of the pineal organ. On the other hand, immunoreactive pinealocytes increased remarkably in the end-vesicle of the organ with age, followed by a gradual expansion toward the proximal portion. Thus, the spectacular increase in NSE-positive pinealocytes and the progressive reduction of reactive neurons occurred in parallel during the course of post-hatching development. NSE-immunoreactive pinealocytes displayed morphological characteristics of bipolar elements, endowed with an apical protrusion into the pineal lumen and a short basal process at younger stages, whereas multipolar types of NSE-positive pinealocytes were predominantly found in the adult domestic fowl. These results indicate that in the pineal organ of the domestic fowl (1) the ontogenetic expansion of NSE-immunoreactive pinealocytes is paralleled by a regressive afferent innervation, (2) the NSE-positive pinealocytes transform from a bipolar (columnar) type to a multipolar type during post-hatching development, and (3) these ontogenetic changes in the NSE-immunoreactivity and morphology of pinealocytes may reflect the development of a neurosecretory-like capacity of the organ.     

Development of the mitochondrial apparatus and blood supply of skeletal muscle fibers during ontogenesis of domestic fowl

The diameter, length, and numerical density of capillaries, diameter of muscle fibers, size and numerical density of their profiles, and relative volume of mitochondria in them were determined in the chicken red oxidative gastrocnemius and white glycolytic pectoral muscle during development from day 10 of embryogenesis to six month of postnatal life. The bulk blood flow was measured in these muscles by hydrogen clearance during postembryonic development. During embryogenesis, the fibers of gastrocnemius muscle develop and grow at a higher rate, while during postembryonic development, those of the pectoral muscle develop faster. The density of mitochondrial profiles increases during embryogenesis and decreases after hatching, while their mean size increases, especially in the oxidative fibers, but it somewhat decreases in 6-month old chicks. Redistribution of mitochondria by the fiber section during development takes place in both muscles: they are localized predominantly in the center in 18-day embryos and in the periphery, especially in the gastrocnemius fibers, in 6-month old fowl. At hatching, the lengths of capillaries are similar in both muscles, but as chicks grow, the proportion of longer (more than 600 microm) capillaries in the pectoral muscle sharply increases, while their density and bulk blood flow decrease. Ratios were determined between structural parameters of the capillary bed and mitochondria, on the one hand, and oxygen consumption (ml/min per 1 mm fiber and 100 g muscle mass), on the other.     

Development of the mitochondrial apparatus and blood supply of skeletal muscle fibers during ontogenesis of domestic fowl

The diameter, length, and numerical density of capillaries, diameter of muscle fibers, size and numerical density of mitochondrial profiles, and relative volume of mitochondria in them were determined in the chicken red oxidative gastrocnemius and white glycolytic pectoral muscle during development from day 10 of embryogenesis to six month of postnatal life. The bulk blood flow was measured in these muscles by hydrogen clearance during postembryonic development. During embryogenesis, the fibers of gastrocnemius muscle develop and grow at a higher rate, while during postembryonic development, those of the pectoral muscle develop faster. The density of mitochondrial profiles increases during embryogenesis and decreases after hatching, while their mean size increases, especially in the oxidative fibers, but it somewhat decreases in 6-month old chicks. Redistribution of mitochondria across the fiber section during development takes place in both muscles: they are localized predominantly in the center in 18-day embryos and in the periphery, especially in the gastrocnemius fibers, in 6-month old chicks. At hatching, the length of capillaries is similar in both muscles, but as chicks grow, the proportion of longer (more than 600 µm) capillaries in the pectoral muscle sharply increases, while their density and bulk blood flow decrease. Ratios were determined between structural parameters of the capillary bed and mitochondria, on the one hand, and oxygen consumption (ml/min per 1 mm fiber and 100 g muscle mass), on the other.__________Translated from Ontogenez, Vol. 36, No. 2, 2005, pp. 135–144.Original Russian Text Copyright © 2005 by Belichenko, Korostyshevskaya, Maksimov, Shoshenko.     

Brain serotonin turnover and plasma prolactin and growth hormone concentrations during changes in osmotic balance in the domestic fowl

Summary Young cockerels injected 24 h earlier with 0.9% saline,para-chorophenylalanine (pCPA, brain serotonin depletor) or alpha-methylpara-tyrosine (AMPT, brain catecholamine depletor) were deprived of access to water for 24 h. Plasma prolactin concentrations were markedly elevated by water deprivation and returned to normal on rehydration. pCPA, but not AMPT, significantly reduced the increase in prolactin. Concentrations of growth hormone were not affected by water deprivation. Brain serotonin concentrations were reduced by treatment with pCPA. Groups of cockerels were maintained under normal conditions or without access to drinking water for 12 h or 24h. Some were injected with the monoamine oxidase inhibitor pargyline, which increased the prolactin and decreased the growth hormone concentration in the plasma of the hydrated birds. The inhibitory effect of pargyline on growth hormone was augmented following water deprivation. Serotonin levels were not significantly affected by water deprivation but turnover (defined as accumulation of serotonin after pargyline treatment) was increased in the hypothalamus but not in remaining tissue. Injecting 30% saline solution intravenously markedly increased plasma prolactin whilst growth hormone concentrations were decreased. Serotonin turnover was increased in the hypothalamus but not in other brain regions. The results show that secretion of prolactin and growth hormone by the pituitary gland during osmotic imbalance in the fowl may be mediated by changes in hypothalamic scrotonin turnover.     

Embryonic development of the domestic guinea fowl (Numida meleagris)

Inside the viable range 36–39°C, the development of the domestic guinea fowl embryo was studied during artificial incubation of about 5000 eggs. Equations giving internal and external pipping and hatching time as a function of incubation temperature were developed. Whatever temperature was used, internal and external pipping occurred at 89% and 95% of hatching time, respectively. The chronological development in ovo of the guinea fowl is illustrated by growth curves. Guinea fowl grew in ovo at the same rate as the chicken embryo. The embryonic mortality is significantly affected by incubation temperature. The thermal tolerance of the embryo follows a parabolic curve: temperatures below or above 37.2°C increase the rate of mortality. During the course of the incubation, the mortality frequency was mainly distributed around two peaks (each one third of the total), which occurred during the first days of incubation, that is, within the first 12% of the incubation time, and during the last days, that is, after 85% of the incubation time. At the optimal 37.2°C temperature, these two peaks occurred on days 1–3 and 23–27, respectively.     

Ultimobranchial gland of the domestic fowl

Summary The ultimobranchial gland (UBG) of birds is particularly rich in calcitonin, the hypocalcaemic hypophosphataemic hormone, that is secreted by the C-cells of the mammalian thyroid. The principal cells of the UBG have a striking resemblance with the mammalian C-cells, i.e., they possess small intracytoplasmic dense-core secretory granules, 150–300 nm in diameter. The gland also contains a second, morphologically distinct, endocrine cell type with larger granules, 500–800 nm in diameter. A sensitive immunocytochemical reaction was developed with the use of antibodies against salmon calcitonin. By means of this technique the presence of calcitonin-immunoreactive molecules was demonstrated in both secretory cell types of the UB gland of the chicken. This gland can thus be considered as a homogeneous calcitonin-producing tissue. Whether the secretory products are identical is discussed and differences in the secretory pathways are suggested.     

The synthesis of o-aminophenyl glucuronide in several tissues of the domestic fowl, Gallus gallus, during development

1. Synthesis of o-aminophenyl glucuronide has been studied in tissues of the domestic fowl, Gallus gallus, during development. 2. The only route of synthesis detected is glucuronyl transfer from UDP-glucuronic acid, and evidence suggests this to be the major pathway. 3. The pathway exists in liver, to a lesser extent in kidney and alimentary tract, and possibly also in skin. It is absent from spleen and adrenal gland. 4. o-Aminophenyl glucuronide formation, UDP-glucuronyltransferase, UDP-glucuronic acid and UDP-glucose dehydrogenase exist in the embryo liver from at least 12 days of incubation. Transferase activity falls just before hatching and rises suddenly on emergence. Overall synthesis of o-aminophenyl glucuronide observed in liver slices confirms this pattern, which also occurs in kidney. UDP-glucuronyltransferase appears in intestinal mucosa only after hatching, and is absent from embryonic spleen. The allantoic membrane forms no o-aminophenyl glucuronide. 5. These findings are related to the isolated existence of an avian embryo.