Ontogeny of cholinergic and adrenergic cardiovascular regulation in the domestic chicken (Gallus gallus)

Adrenergic and cholinergic tone on the cardiovascular system of embryonic chickens was determined during days 12, 15, 19, 20, and 21 of development. Administration of the muscarinic antagonist atropine (1 mg/kg) resulted in no significant change in heart rate or arterial pressure at any developmental age. In addition, the general cardiovascular depressive effects of hypoxia were unaltered by pretreatment with atropine. In addition, the ganglionic blocking agent hexamethonium (25 mg/kg) did not induce changes in heart rate. The beta-adrenergic antagonist propranolol (3 mg/kg) induced a bradycardia of similar magnitude on all days studied, with a transient hypertensive action on days 19-20, indicating the existence of an important cardiac and vascular beta-adrenergic tone. Injections of the alpha-adrenergic antagonists prazosin or phentolamine (1 mg/kg) reduced arterial pressure significantly on all days of incubation studied. Collectively, the data indicate that embryonic chickens rely primarily on adrenergic control of cardiovascular function, with no contribution from the parasympathetic nervous system.     

Expression profiling of candidate genes for abdominal fat mass in domestic chicken Gallus gallus

The quantitative traits of mass and percentage of abdominal fat in chicken and various types of obesity in mammals are homologous and functionally similar. Therefore, the genes involved in obesity development in humans and laboratory rodents as well as those responsible for pig lard thickness could be involved in abdominal fat deposition in broilers. Expression of candidate genes FABP1, FABP2, FABP3, HMGA1, MC4R, PPARG, PPARGC1A, POMC and PTPN1 was studied in fat, liver, colon, muscle, hypophysis, and brain in chicken (broilers) using real-time PCR. Significant difference in the HMGA1 gene expression in the liver of broiler chicken with high (3.5 +/- 0.18%) and low (1.9 +/- 0.56%) abdominal fat concentration has been revealed. The expression of this gene was been shown to correlate with the amount (0.7, P < or = 0.01) and mass (0.7, P < or = 0.01) of abdominal fat. The PPARG gene expression in liver in the same chicken subsets was also significantly different. Correlation coefficients of the gene expression with the abdominal fat amount and mass were respectively 0.55 (P < or = 0.05) and 0.57 (P < or = 0.01). Based on these results, we suggest that the HMGA1 and PPARG genes are involved in abdominal fat deposition. The search for single nucleotide polymorphisms (SNPs) in the HMGA and PPARG regulatory regions could facilitate identifying genetic markers for broiler breeding according to the mass and percentage of abdominal fat.     

Sex inversion in domestic chicken (Gallus gallus domesticus) by letrozole and tamoxifen

In multicellular organisms, determination of sex identity is a complex, multistage process. Sex hormones are synthesized in gonads and fulfill the role of inductors in this process. The effect of androgen is currently well studied. However, the participation of estrogen in the formation of female gonads and female sex on the whole is not much known. Here, we present the results of experimental sex inversion by inhibition of aromatase (an enzyme involved in estrogen synthesis) and tamoxifen (a modulator of estrogen receptors) in chick embryos. It was shown that masculinization depended on the dose of the substance and quantity of injections. Inhibition of aromatase did not block the meiotic prophase in oogoniums. It has been suggested that retinoic acid and estrogens have different mechanisms of effect on oogenesis. Proteins and nucleoproteins interacting with estrogen receptor 1 and their gene localization in human and chicken genomes have been shown for the first time.     

Genetic characterization of Bhutanese native chickens based on an analysis of Red Junglefowl (Gallus gallus gallus and Gallus gallus spadecieus), domestic Southeast Asian and commercial chicken lines (Gallus gallus domesticus)

The genetic diversity of Bhutanese chickens needs to be understood in order to develop a suitable conservation strategy for these birds in Bhutan. In this, work, we used microsatellite markers to examine the genetic diversity of Bhutanese chickens. Four Bhutanese chicken varieties (Black plumage, Frizzle, Naked neck and Red Junglefowl-like, corresponding to Yuebjha Narp, Phulom, Khuilay and Seim, respectively), two subspecies of Red Junglefowl (Gallus gallus gallus and Gallus gallus spadecieus), two varieties of Thai native chickens (Pradhu Hang Dam and Chee; Gallus gallus domesticus) representing the Southeast Asian domestic chicken, and two commercial lines (Broiler and Single Comb White Leghorn) were genotyped with 18 microsatellites that included 16 loci recommended by the FAO/ISAG for investigations of genetic variability in chickens. All loci were polymorphic, with the number of alleles ranging from six (MCW0111) to 23 (MCW0183). Substantial genetic variation was observed in all populations, with the Bhutanese native chicken Yuebjha Narp (Black plumage chicken) showing the lowest genetic variability. Despite extensive intrapopulation variation, the genetic differentiation among 10 populations was moderate. A neighbor-joining tree revealed the genetic relationships involved while principal component analysis showed that Bhutanese native chickens should be given priority in conservation efforts because of their genetic distinctiveness. Chee chickens are especially valuable as a reservoir of predomestic diversity, as indicated by their greater genetic variation and their position in the phylogenetic tree.     

Parameters of the chicken genome (Gallus gallus)

As more information on the chicken genome is gathered, it is becoming increasingly more important to be able to correlate genetic and physical maps. Quantitation of the chicken karyotype is important in establishing parameters which define the genome. Here we report on the physical lengths of the chicken macrochromosomes and establish the DNA content of each, thus identifying implicitly how much of the genome is represented by the microchromosomal component. For the first time, genetic and physical data on the chicken karyotype are presented in relation to one another.     

Morphogenesis and reaction to hypoxia of atrial myoendocrine cells in chick embryos (Gallus gallus)

Ultrastructural and stereomorphometric study of the chick embryo right atrium at the 14th day of incubation has shown cardiomyocytes to divide mitotically and to be at different stages of differentiation. The cytoplasm of some muscle cells contains secretory granules that by sizes and morphology can be classified as formed, mature, and dissolved forms. By the 18th day of incubation the majority of cardiomyocytes is already differentiated, and the amount of their secretory granules increases. Under conditions of hypoxia, after three days, in myoendocrine cells there are noted features of accelerated secretion of the peptides that are synthesized earlier and are accumulate in the granules, while after one weak—features of acceleration of their synthesis. It can be concluded that in chick embryos, at least from the 14th day of incubation, the system of the heart natriuretic peptides participates in regulation of hemodynamics and of water—salt balance and responds to hypoxia.     

Prenatal exposure to testosterone impairs oxidative damage repair efficiency in the domestic chicken (Gallus gallus)

Elevated levels of maternal androgens in avian eggs affect numerous traits, including oxidative stress. However, current studies disagree as to whether prenatal androgen exposure enhances or ameliorates oxidative stress. Here, we tested how prenatal testosterone exposure affects oxidative stress in female domestic chickens (Gallus gallus) during the known oxidative challenge of an acute stressor. Prior to incubation, eggs were either injected with an oil vehicle or 5 ng testosterone. At either 17 or 18 days post-hatch, several oxidative stress markers were assessed from blood taken before and after a 20 min acute stressor, as well as following a 25 min recovery from the stressor. We found that, regardless of yolk treatment, during both stress and recovery all individuals were in a state of oxidative stress, with elevated levels of oxidative damage markers accompanied by a reduced total antioxidant capacity. In addition, testosterone-exposed individuals exhibited poorer DNA damage repair efficiencies in comparison with control individuals. Our work suggests that while yolk androgens do not alter oxidative stress directly, they may impair mechanisms of oxidative damage repair.     

Neurogenic inflammation in the chicken (Gallus gallus var domesticus)

1. Neurogenic inflammation has been studied in the anaesthetized adult hen using a variety of different stimuli.2. Plasma extravasation was produced following antidromic stimulation of the external mandibular ramus of the trigeminal nerve which innervates the skin at the angle of the jaw and the anterior part of the wattle.3. Stimulation of the wattle by external application of mustard oil, thermal and mechanical stimuli, as well as intradermal injection of substance P and bradykinin, all produced plasma extravasation.4. These results demonstrate that, in contrast to previous findings in the pigeon, at least in the trigeminal of the chicken peripheral C-fibre nociceptors have similar physiological characteristics in relation to the neurogenic inflammatory mechanism to those seen in mammals.     

Age-related changes of the somatotrophs of the domestic fowl Gallus gallus

Summary The ultrastructure of the somatotrophs of the caudal pituitary of the domestic fowl was studied quantitatively. Two age groups of male chickens were compared: 4–6 weeks and 24–30 weeks post-hatching. With age, somatotrophs decreased from about 40% to about 30% of the pituitary cell population. Their volume density decreased similarly. Mean volume of a somatotroph was the same in young and adult animals. Because the granule volume density of the somatotrophs was unchanged, but the somatotroph volume density of the gland declined, the granule volume density of the caudal pituitary gland dropped in parallel with that of the somatotrophs. Thus the volume of the gland comprised of somatotroph granules fell about 32%: from 6.57% to 4.45%. This lowered pool of stored hormone may be linked to the lowered circulating levels of growth hormone found in older animals by other investigators.The granule volume density of the somatotrophs was unchanged but the numerical density approximately doubled; thus the mean granule size decreased by 47% with age. The relationship of the size reduction of the granules to the lowered plasma growth hormone levels is not understood at present.Supported in part by Hatch and State funds from the New Jersey State Agricultural Experimental Station and NSF grants PCM 8,0227,27 and PCM 8,302197.     

Surface morphology of basilar papilla of the tufted duck Aythya fuligula,and domestic chicken Gallus gallus domesticus

Quantitative details of the surface morphology of the hearing organ, the Papilla basilaris, as seen in the scanning electron microscope are described for the tufted duck Aythya fuligula and for comparison for the domestic chicken Gallus gallus domesticus, for which some published information is already available. As in the other avian species investigated to date, each papilla shows a unique constellation of features. The papilla of the tufted duck is 3.5 mm long in the unfixed state and contains 8,200 sensory hair cells. It shows systematic changes in its surface features along the length and across the width of the sensory epithelium. In general, its features and those of the chicken Papilla basilaris can be described as relatively primitive in comparison with other species. The tufted duck papilla does, however, show one feature that has so far been found to be well developed only in advanced papillae; the number of stereovilli per hair cell bundle is generally much higher on hair cells of the neural than those on the abneural side. This difference is only weakly developed in the chicken. It is clear that features considered to be evolutionarily advanced were acquired independently of one another during evolution and that each bird species can show a mosaic of primitive and advanced features. © 1996 Wiley-Liss, Inc.     

The primary sequence of chicken myoglobin (Gallus gallus).

After enzymatic digestion of chicken myoglobin by trypsin, chymotrypsin or thermolysin, the separation of peptides was performed by column chromatography on various ion exchange resins. Each peptide was purified by high-voltage paper electrophoresis or by chromatography either on paper or on ion-exchange resin, and its complete amino acid sequence was then determined by the combined dansyl-Edman procedure and by endopeptidase digestions. The whole globin was submitted to automatic Edman degradation using the Beckman sequencer. Residues have been positioned from overlaps of sequence data between tryptic (T), chymotryptic (C) and thermolysin (Th) peptides. The stepwise degradation of the whole globin confirmed the alignment of the N-terminal third of the molecule. The combination of these different approaches has led to the complete determination of the 153 residues sequence forming the polypeptide chain of chicken myoglobin. Comparison of the established chicken myoglobin structure with those from other species shows a conservation of structure, although the avian protein exhibits more variations in its amino acid sequence than has been found between other known myoglobins which all belong to mammalian species.     

Development of the innervation in the chicken pineal gland (Gallus gallus).

The innervation of the pineal gland has been studied during the embryonic development and the first 10 days after hatching. On day 17 of embryonic development, the first nerve fibers are observed in the pineal capsule. They appear at the stalk level and rise to locate mostly on the anterior side of the capsule. Some nerve fibers leave these nerve bundles to penetrate the gland and they situate in the connective septa (18 days of development). From day 19 of development onwards, nerve fibers locate only in the parafollicular layer. Cells that may be identified as neurons are found in the pineal parenchyma.     

The action of insulin in the morphogenesis of Gallus gallus domesticus embryos]

Aspects concerned with morphogenesis of Gallus gallus domesticus, avail studies related to the action of the insulin in the topography and embryonic structures. At the temperature of 37.5 degrees C, eggs were incubated during 24 h, injected with 5 ml of swine insulin in three concentrations and reincubated for more 72 h. The morphological characteristics of 80 embryos were evaluated and, according to the presented organization, classified in 5 morphogenetic levels. It was registered generalized dysmorphism (4th level) in 21 embryos that went through the tests with insulin. Standard morphogenesis (1st level) and located dysmorphism (3rd level) were verified among those from the control experiments. Those individuals concerned with the 4th level, showed reduced dimension of the body and were characterized by anterior-dorsal limits organized in a cephalic projection, and also presented alterations in the posterior-ventral region. These features evidence a pattern of abnormality in the determination of the cephalic-caudal axis and indicate a specific action of the insulin in the embryonic morphogenesis, in the period of 96 hours of incubation.     

Development of an auditory discrimination in domestic chicks (Gallus gallus)

Ninety-two chicks were exposed to two different sounds, one of which was paired during training with a conspicuous visual stimulus. Visual stimuli maintained subsequent responses to the auditory stimuli, whereas responses to discriminably different sounds that were not paired with visual stimuli habituated. Auditory discriminations were learned at 1 day of age both by chicks that were previously ‘imprinted’ to the visual stimulus and by those that were not. Only the visually imprinted chicks performed significantly better than random when trained at 2 or 3 days, indicating an early critical period for visual, but not auditory, stimuli. It is suggested that visual stimuli enhance responses to species-typical and individually distinctive vocalizations.     

Ultrastructural study of the pineal gland of the chicken (Gallus gallus).

The authors studied the pineal glands of chickens (Gallus gallus) between the ages of 2 and 5 days with the electron microscope. They described two distinct areas in the parenchyma of the organ: the follicles, formed by two cellular categories, the pineal A and B cells, and the parafollicular zone, which surrounds and separates the follicles from the connective walls. This area is formed, fundamentally, by two types of cells and nerve fibers. These cells occasionally delimit cavities. We propound the hypothesis of the possible transformation of the parafollicular zone into follicles.     

A histochemical study of keratinization in the domestic fowl (Gallus gallus)

The microanatomy of the epidermis of the domestic fowl is described and related to the distribution of various histochemical constituents involved in keratinization.
The avian horny layer over the back is composed of a loose network of structurally solid horny cells. This is in contrast to most mammalian epidermal horny cells in which structural keratin is found only in the peripheral cytoplasm, and the interior of the keratinocyte contains soluble products of cytolysis with possibly some free keratin filaments dispersed in the fluid material.
The avian tarsal epidermal horny scales show similarities to both the scales of lizards and snakes and to mammalian tail scales which appear to be homologous structures.
It is suggested that a thin layer of cells containing no detectable disulphide bonds, found in the tarsal scale region of the young chick, is probably mechanically weak and may function as a fission plane for sloughing of the horny layer. A specialized epidermis and thickened horny layer is developed in the fowl on the plantar underside of the toes, but this is quite different in structure from the mammalian plantar epidermis.
The overlapping of zones rich in ribonucleic acid (RNA) and bound cysteine (SH) in the growing feather suggests that protein synthesis and the preparatory stages to keratin disulphide bonding normally occur concurrently in feather formation. This is in contrast to the growing hair which has a region rich in RNA followed immediately before it becomes keratinized by a discrete keratogenous zone weak in RNA but rich in bound cysteine.     

Systematic identification and characterization of chicken (Gallus gallus) ncRNAs

Recent studies have demonstrated that non-coding RNAs (ncRNAs) play important roles during development and evolution. Chicken, the first genome-sequenced non-mammalian amniote, possesses unique features for developmental and evolutionary studies. However, apart from microRNAs, information on chicken ncRNAs has mainly been obtained from computational predictions without experimental validation. In the present study, we performed a systematic identification of intermediate size ncRNAs (50–500 nt) by ncRNA library construction and identified 125 chicken ncRNAs. Importantly, through the bioinformatics and expression analysis, we found the chicken ncRNAs has several novel features: (i) comparative genomic analysis against 18 sequenced vertebrate genomes revealed that the majority of the newly identified ncRNA candidates is not conserved and most are potentially bird/chicken specific, suggesting that ncRNAs play roles in lineage/species specification during evolution. (ii) The expression pattern analysis of intronic snoRNAs and their host genes suggested the coordinated expression between snoRNAs and their host genes. (iii) Several spatio-temporal specific expression patterns suggest involvement of ncRNAs in tissue development. Together, these findings provide new clues for future functional study of ncRNAs during development and evolution.     

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.