Newly-hatched Chick Research Articles

FcRY is a key molecule controlling maternal blood IgY transfer to yolks during egg development in avian species.

Maternal immunoglobulin transfer plays a key role in conferring passive immunity to neonates. Maternal blood immunoglobulin Y (IgY) in avian species is transported to newly-hatched chicks in two steps: 1) IgY is transported from the maternal circulation to the yolk of maturing oocytes, 2) the IgY deposited in yolk is transported to the circulation of the embryo via the yolk sac membrane. An IgY-Fc receptor, FcRY, is involved in the second step, but the mechanism of the first step is still unclear. We determined whether FcRY was also the basis for maternal blood IgY transfer to the yolk in the first step during egg development. Immunohistochemistry revealed that FcRY was expressed in the capillary endothelial cells in the internal theca layer of the ovarian follicle. Substitution of the amino acid residue in Fc region of IgY substantially changed the transport efficiency of IgY into egg yolks when intravenously-injected into laying quail; the G365A mutant had a high transport efficiency, but the Y363A mutant lacked transport ability. Binding analyses of IgY mutants to FcRY indicated that the mutant with a high transport efficiency (G365A) had a strong binding activity to FcRY; the mutants with a low transport efficiency (G365D, N408A) had a weak binding activity to FcRY. One exception, the Y363A mutant had a remarkably strong binding affinity to FcRY, with a small dissociation rate. The injection of neutralizing FcRY antibodies in laying quail markedly reduced IgY uptake into egg yolks. The neutralization also showed that FcRY was engaged in prolongation of half-life of IgY in the blood; FcRY is therefore a multifunctional receptor that controls avian immunity. The pattern of the transport of the IgY mutants from the maternal blood to the egg yolk was found to be identical to that from the fertilized egg yolk to the newly-hatched chick blood circulation, via the yolk sac membrane. FcRY is therefore a critical IgY receptor that regulates the IgY uptake from the maternal blood circulation into the yolk of avian species, further indicating that the two steps of maternal-newly-hatched IgY transfer are controlled by a single receptor.

Effects of Peroral Microbiota Transplantation on the Establishment of Intestinal Microorganisms in a Newly-Hatched Chick Model

This study was carried out to compare gut microbial community composition, diversity, and function with and without microbiota transplantation in a newly-hatched chick model. Two hundred and forty newly-hatched Arbor Acre male broilers were assigned randomly to either a microbiota transplantation group or a control group (n = 120; 6 replicates per group, and 20 broilers per replicate). Both groups were fed a basal diet that met all nutritional requirements, composed of corn, soybean meal, cottonseed meal, vitamins, and minerals. The microbiota transplantation group was inoculated with the microbiota from the ceca of healthy adult chicks on day 1 and 2, respectively, over a trial period of 42 d. For both groups, the numbers of total bacteria, Lactobacillus and Escherichia coli, operational taxonomic unit partitioning and classification, taxonomic composition, comparative microbiota, and key bacterial species were identified by a 16S rRNA sequencing analysis. The results showed that Aestuariispira, Christensenella, Fervidicella, Gracilibacter, Haloferula, Mycoplasma, Novispirillum, and Pantoea were more abundant (p < 0.05) in the microbiota transplantation group than those in the control group. This indicates that microbiota transplantation could directly influence the abundances of specific bacterial taxa in the ileum and cecum of broilers. These findings provide insight into the modulation of gut health for patients with abnormal bowel function, which should be of great interest to researchers in the area of gastroenterology, applied microbiology, and animal sciences.

Long-Lasting Effects of Incubation Temperature During Fetal Development on Subcutaneous Adipose Tissue of Broilers.

Increasing evidence indicates that fetal programming may cause permanent effects on offspring adipose tissue and body composition. Previous study showed reduction in newly-hatched broiler chick adiposity by manipulating incubation temperature during fetal development. The present study examined whether incubation temperature during fetal development has long-term effects on post-hatching fat deposition in broilers. Broiler breeder eggs (Cobb-500®) were incubated under constant low (36°C, LT), control (37.5°C, CT) or high (39°C, HT) temperature from day 13 onward, giving to eggshell temperature of 37.3 ± 0.08°C, 37.8 ± 0.2°C, and 38.8 ± 0.3°C, respectively. Male chicks were reared under recommended temperatures until 42 days old. LT 21 days old broilers exhibited higher blood cholesterol than CT broilers, and higher triglycerids, VLDL, and LDL, and lower HDL than CT and HT broilers. LT broilers presented higher liver cholesterol than CT broilers and lower ether extract percentage than CT broilers. Adipocyte count was lower in the abdomen than in the thigh. Until day 21 of age, feed intake was higher in LT than in HT broilers. At day 42 of age, blood cholesterol and LDL were higher in HT broilers than in CT and LT broilers. Liver cholesterol was higher in LT than in HT broilers. LT treatment reduced neck and increased thigh adipocyte size compared to CT treatment, while the HT treatment reduced abdomen and neck adipocyte size compared to other two treatments and in the thigh compared to LT treatment. In CT broilers, thigh adipocytes were smaller than abdomen and neck adipocytes. HT treatment increased adipocyte number per area in the neck compared to LT and CT treatment, and LT and HT treatments reduced adipocyte count in the thigh compared to CT treatment. CT broilers presented higher adipocyte count in the thigh than the abdomen and neck, while HT broilers presented higher adipocyte count in the neck than the abdomen and thigh. Cell proliferation was lower in the abdomen than in the thigh. The results show incubation temperature manipulation during fetal development has long-term and distinct effects on regional adiposity, and can be used to modulate broiler fat deposition.

Expression of insulin-like growth factor 1 receptor in rat retina following optic nerve injury

To investigate the apoptosis in retinal ganglion cells (RGCs) and insulin-like growth factor 1 receptor (IGF-1R) in the retina following optic nerve crush. Healthy Wistar rats (N = 70) were divided into two groups: a normal control group and an optic nerve injury group. Immunohistochemistry and flow cytometry were performed to detect the expression of IGF-1R and to measure the apoptosis of RGCs, respectively. Immunohistochemistry revealed that at 1 hr after optic nerve injury, IGF-1R immunoreactivity began to increase and reached a maximal level at 24 hr (p < 0.05), where it remained elevated up to 14 days after injury. RGC apoptosis in the normal control group was 0.53%, while the apoptosis rate in the optic nerve injury group increased over time. The apoptosis rate in the optic nerve injury group was 1.4% at 1 hr, 4.4% at 6 hr, 5.2% at 12 hr and reached a maximal level (8.5%) at 24 hr. Subsequently, the rate declined to 1.9% 7 days after injury and 0.9% 2 weeks after injury. The IGF-1R immunereactivity in the retina increased after optic nerve injury. IGF-1R may regulate the apoptosis and regeneration of RGCs at different stages after optic nerve injury.

Molecular function of microtubule-associated protein 2 for filial imprinting in domestic chicks ( Gallus gallus domesticus)

RNA interference (RNAi)-mediated gene-silencing can be a tool for elucidating the role of genes in the neural basis of behavioral plasticity. Previously, we reported that exogenous DNA could be successfully delivered into newly-hatched chick brains via electroporation. Here, we used this in vivo gene-transfer technique and showed that transfected microRNA vectors preferentially silence exogenous DNA expression in neuronal cells. Using this system, the up-regulation of microtubule-associated protein 2 (MAP2) accompanying filial imprinting was suppressed in vivo, which impaired the filial imprinting in chicks. In addition, the phosphorylation of MAP2 was found to increase in parallel with filial imprinting, and lithium chloride, an inhibitor of glycogen synthase kinase 3 (GSK3), was found to impair filial imprinting. Our results suggest that the regulation of MAP2 expression and its phosphorylation are required for filial imprinting and may modify microtubule stability, thereby leading to cytoskeletal reorganization during imprinting. This in vivo RNAi-mediated gene-silencing system will facilitate the analysis of gene function in the living chick brain and provides further clues regarding the molecular mechanisms underpinning avian learning.

Progesterone receptor isoforms in ovary of newly-hatched chick after gonadotropin treatment during embryonic development

We evaluated by immunohistochemistry the expression of progesterone receptor (PR) isoforms in different cell subpopulations of the ovary of newly-hatched chicks after a treatment with Follicle-stimulating hormone (FSH) or Luteinizing hormone (LH) administered on days 13, 15 and 17 of embryonic development. Two monoclonal antibodies that recognize either both PR isoforms or only PR-B, were used. The results indicate that FSH increased both the total number of cells and the number of PR-immunoreactive ones in all cell subpopulations of the ovary. In all cases, PR-B was the isoform regulated by FSH. In contrast, LH did not modify the number of total cells in any cell subpopulations of the ovary. Besides, LH decreased the number of PR-B immunoreactive interstitial cells, without modifying PR expression in any other cell subpopulations of the ovary. These results reveal differential effects of FSH and LH on PR-expression in cell subpopulations of the ovary of newly hatched chicks treated during embryonic development. We conclude that gonadotropins regulate PR-B isoform in the prefollicular ovary of the chick.

Selective excretion of yolk-derived tocotrienols into the bile of the chick embryo

The aim of this study was to investigate the possibility of biodiscrimination between different forms of vitamin E during the development of the chick embryo. The vitamin E present in the initial yolk consisted of α-tocopherol (90%), ( β+ γ)-tocopherol (8%), α-tocotrienol (0.3%) and ( β+ γ)-tocotrienol (1.3%). In marked contrast, the vitamin E recovered from the bile of the day-16 embryo contained much higher proportions of α-tocotrienol (10%) and especially of ( β+ γ)-tocotrienol (42%). By the time of hatching, 56% of the vitamin E present in the bile was in the form of ( β+ γ)-tocotrienol. The residual yolk of the newly-hatched chick contained far greater proportions of α-tocotrienol (2.6%) and ( β+ γ)-tocotrienol (10%) than were present in the initial yolk. The results suggest that the liver of the embryo may selectively excrete tocotrienols as components of bile, whilst retaining the tocopherols within the hepatocytes. The increased proportions of tocotrienols in the residual yolk may result from the recycling of bile from the gall bladder to the yolk. The liver of the day-old chick contained α-tocopherol as the main form of vitamin E (90%) with only a small proportion (0.2%) of ( β+ γ)-tocotrienol. The α-tocopherol form was also the main vitamin E component in the brain (85%), heart (79%), lung (82%) and adipose tissue (91%) of the day-old chick. The present study suggests the occurrence of a high degree of biodiscrimination between tocopherols and tocotrienols during the development of the chick embryo.

Influence of Intracerebroventricular Administration of Exendin (9-39) on Food Intake of the Newly-Hatched Chick.

The present study was done to elucidate whether central administration of exendin (9-39), a specific glucagon-like peptide-1 (GLP-1) receptor antagonist in mammals, alters food intake of the neonatal chick. Intracerebroventricular administration of exendin (9-39) at the levels of 0.5, 1 and 2μg did not alter food intake of chicks compared with the saline control. It is concluded that modification of a part of amino acid sequence of exendin (9-39) may be required to antagonize chicken GLP-1 receptor.

Biogenesis and content of rhodopsin in the retina of the chick during development.

Developmental aspects of the formation of rhodopsin in the chick were investigated. The content of rhodopsin was measured in the retina of the developing chick embryo, newly hatched and adult chickens by both spectral and immunological procedures. Rhodopsin was first detected spectrally at day 18 (stage 43) with the level increasing about 6 fold through hatching. The concentration in the adult retina was about one half that present in the 1 day old chick. By the more sensitive procedure of radioimmunoassay (RIA), rhodopsin was detected as early as day 12 (stage 37), but was undetectable in the 8 day old embryo. The rhodopsin concentration remained low and relatively constant until day 17 (stage 42), at which point it increased rapidly up to hatching. Retina from the newly-hatched chick had a rhodopsin concentration some 30 fold higher than the 16 day old embryo (stage 41). The results of RIA indicate that the biosynthesis of rhodopsin may significantly precede the morphological appearance of outer segments.

On the nerve plexus of the chicken gizzard.

The Auerbach's plexus of the gizzard was stained in toto in adult chicken and in young and newly-hatched chicks. The plexus lies immediately beneath the serosa and extends over 55% of the surface of the organ, covering its cranial and caudal poles and the two curvatures. The areas into which the plexus does not extend (i.e., most of the ventral and the dorsal surface) are those where the muscle is covered by the laminar tendon of the gizzard. The ganglia are large, often with hundred of neurons, and have short and broad connecting strands. They are surrounded by a capsule of connective tissue. The ganglion neurons are discoidal and in the adult they measure up to 50 microns in diameter, each being surrounded by a set of glial cells. A few small neurons persist in the adult; in the newly-hatched chick these are predominant, but some large neurons up to 25 microns in diameter are already present. The ultra-structural features of the ganglia of the Auerbach's plexus include the abundance of axo-somatic synapses, as well as numerous axo-dendritic synapses, the presence of intra-ganglionic bundles of collagen fibrils and blood vessels, the abundance of glial cells. In addition to the plexus beneath the serosa, the gizzard has many small intramuscular ganglia located throughout the musculature (which is exclusively circular). These ganglia do not have a connective tissue capsule and are made of small and tightly packed neurons.

The onset and development of descending pathways to the spinal cord in the chick embryo.

The ontogenetic development of afferent (supraspinal and propriospinal) as well as efferent (ascending) fiber connections of the spinal cord was examined following the injection of horseradish peroxidase (HRP) or wheat germ agglutinin HRP (WGA-HRP) into the cervical and lumbar spinal cords (or brains) of embryos ranging in age from 4 to 14 days of incubation. A few cells were first reliably retrogradely labelled in the pontine reticular formation on embryonic day (E) 4 and E5 following the injection of WGA-HRP into the cervical and lumbar spinal cord, respectively. Propriospinal projections to the lumbar spinal cord, originating from brachial spinal cord, were found by E5, and from the cervical spinal cord by E5.5. Ascending fibers arising from neurons in the lumbar spinal cord could be followed to rostral mesencephalic levels in E5 embryos. Thus, the earliest supraspinal, propriospinal, and ascending fiber connections appear to be formed almost simultaneously. Retrogradely labelled cells were found in the raphe, reticular, vestibular, interstitial, and hypothalamic nuclei in E5.5 embryos following lumbar injections of WGA-HRP. Except for neurons in cerebellar nuclei, all the cell groups of origin that project to the cervical spinal cord of posthatching chicks were also retrogradely labelled by E8. There was a delay in the time of appearance of the projections from various regions of the brain stem to the lumbar versus the cervical spinal cord, ranging from 0.5 to 7 days, but typically of about 3 days duration. A large number of cells located in the ventral hypothalamic region, just dorsal to the optic chiasma, were found to be labelled following cervical HRP injection between E6 and E10. These cells may represent transient projections that are present only during embryonic stages since no labelled cells were found in this region in the newly-hatched chick.

Experimental gastroenteritis in newly-hatched chicks infected with Campylobacter jejuni.

The susceptibility of chicks to enteritis caused by Campylobacter jejuni was studied. Three-day-old chicks did not develop enteritis after oral infection but chicks infected within 12 h of hatching developed gastroenteritis. The incubation period correlated with the inoculum size. Initially, infected chicks developed blood- and mucus-containing stools, although watery diarrhoea often occurred late in the course of the disease. Recurrences of the enteric manifestations were common but only two out of 170 infected chicks died. C. jejuni was recovered from sites throughout the intestine; the highest concentrations were present in the caecum and large intestine. Both the upper and lower gastrointestinal tract were affected and cellular infiltration of the gastric mucosa and the intestinal lamina propria was observed. Organisms resembling C. jejuni were seen within the intestinal epithelium and lamina propria by electronmicroscopy. The newly hatched chick provides a reproducible and sensitive model of campylobacter enteritis.

Apparent adoptive immune enhancement by bone marrow and bursa of fabricius cells from juvenile chickens

The occurrence of enhancer cells (EC) in the bone marrow and bursa of Fabricius of unprimed and mouse erythrocyte (MRBC) primed birds was investigated. EC are defined operationally as immunocompetent cells that are incapable of adoptive immunity in embryo hosts but able to enhance the immune responsiveness of newly-hatched chick recipients. Weak to moderate immune enhancement was observed in chick hosts grafted with bursal cells from unprimed or MRBC-primed donors whereas with bone marrow cell transfer the immune enhancement was weak with cells from unprimed donors but modest to strong with those from primed donors. Thus antigen priming of donors had little effect on the EC level of the bursa but appeared to increase that in the bone marrow. Moreover, the EC activity of bone marrow of primed donors was donorage dependent. Response profile studies revealed that the EC level of donor bone marrow was low the first 2–3 days after immunization and high by day six. The elevated EC level in the bone marrow of immunized donors is believed due to both recruitment of immigrant cells of extramedullary origin and clonal expansion of medullary immunocompetent cells.

Electron microscopic histochemistry of alkaline phosphatase activity in the developing chick retina

The present paper describes ultrastructural localization of non-specific alkaline phosphatase (ALPase) activity in the chick retina during late embryonic development and after hatching. In the newly-hatched chick retina, intense ALPase activity was found in the outer plexiform layer (OPL), and a less intense reaction was found in the ganglion cell layer and at the outer limiting membrane. Electron microscopic histochemistry revealed that bipolar and horizontal dendrites within the OPL displayed intense reaction product along their plasma membranes. Only horizontal cells showed reaction product on almost their whole circumference. Müller cells also showed reaction product on the plasma membrane in the ganglion cell layer and on the microvilli at their apical portion. The reaction product in the OPL was first recognizable in the retina of the 13- to 14-day-old embryonic chick, and its intensity increased during further development. Little reaction product was found in Müller cells at the embryonic stage. The function of ALPase activity is discussed in relation to the development of the OPL and the nutrient supply for the neural retina.

Dopaminergic cell differentiation in the developing chick retina

The distribution and morphology of dopaminergic (DA) neurons in the chick retina was studied in the course of development. Fluorescent DA cells were first detected on the 13th day of incubation. They were always found in positions two or three cell rows externally from the junction between the inner plexiform layer (IPL) and inner nuclear layer (INL). On the 14th day, DA cells were found in the innermost row of the INL. Subsequently their processes extended not only bilaterally along the IPL-INL junction but also vertically into the IPL. As a result, three fiber layers were formed as laminae 1, 3 and 5 in the IPL. In the newly-hatched chick retina, a number of growth cone-like fluorescent structures with fine spikes were seen at the IPL-INL junction, indicating that DA fibers were still growing and elongating at least at hatching. On the 4th postnatal day, the ramification of dendritic processes was very prominent and they often showed a spiral configuration.

Ontogeny of a circadian rhythm in the glycaemic response of Gallus domesticus to glucagon

1. 1. A circadian rhythm in the glucagon-mediated glycogenolytic response was absent in the newly-hatched chick but was present in the bird aged 1 week. 2. 2. The peak glucose concentration was 38% higher in the afternoon in 1-week-old birds and 50% in 2-week-old birds. 3. 3. The circadian rhythm was not present in 1-week-old birds subjected to constant illumination from hatching. 4. 4. Starving the bird reduced the response to glucagon, irrespective of the time of day.

Ontogeny of a circadian rhythm in the lipacidaemic response of Gallus domesticus to glucagon

1. 1. A circadian rhythm in the glucagon-mediated lipacidaemic response was absent in the newly-hatched chick but was present in the bird aged 1 week. 2. 2. The peak plasma FFA concentrations of morning and afternoon birds aged 1 week were similar but that of the former was maintained for a longer period. 3. 3. The circadian rhythm did not develop in birds subjected to constant illumination; the hyperlipacidaemia was also decreased, irrespective of the time of day. 4. 4. The apparent sensitivity of the bird to glucagon increased during the first week in birds subjected to either 12- or 24-hr photoperiods.

Utilization of 3-hydroxybutyrate by chick cerebral hemispheres during postnatal maturation

1. 1. The utilization of 3-hydroxybutyrate has been studied in the chick telencephalon during its post-hatching maturation. 2. 2. In the 1-day-old chick the blood concentration of 3-hydroxybutyrate appears to be relatively high and its value is 5 times that estimated in the 4- and 30-day-old chicks. 3. 3. The determination of the cerebral arteriovenous differences of 3-hydroxybutyrate shows that the brain of the newly-hatched chick takes up 3 times more actively this ketone body than the brain of the 4-day-old bird does. 4. 4. During incubation in a non-oxygenated and an oxygenated physiological medium, in the presence of 3-hydroxy [3- 14C]butyrate, the specific radioactivity of the dicarboxylic amino acids in the 1-day-old chick brain slices is higher than in those of the the 30-day-old chick, particularly in the oxygenated medium. 5. 5. Thirty minutes after a subcutaneous injection of 3-hydroxy [3- 14C]butyrate, the specific radioactivity of the dicarboxylic amino acids in the 1-day-old chick telencephalon is 3–4 times higher than that in the 4- and 30-day-old chick. 6. 6. In conclusion, in the brain of the newly hatched chick, 3-hydroxybutyrate is an efficient precursor in the biosynthesis of dicarboxylic amino acids, particularly glutamate, and, as glucose, it is metabolically related to the “large compartment” of glutamate. 7. 7. These results have been discussed comparatively to those previously obtained in the developing rodent brain.

Effects of forebrain ablations on avoidance learning in chicks

The involvement of several regions of the newly-hatched chick's forebrain in mediating a learned avoidance response was investigated. Ablations of the posterolateral portion of the telencephalon resulted in complete loss of retention and relearning of the task. Dorsomedial ablations that included parts of the hyperstriatal complex caused a deficit in new learning but not in the retention of a presurgically acquired experience. In contrast, frontal ablations impaired retention and relearning of a preoperatively learned response but did not affect acquisition in chicks initially trained after surgery. These and other findings suggest that telencephalic structures in birds and mammals presumed to share a common phylogenetic ancestry may play analogous roles in the behavior of the two classes.

Tract specificity in the structure of down feathers of the newly-hatched chick.

Comparative study of completed down feathers from seven of the major tracts of newly-hatched Silver Campine chicks reveals tract-specific differences in the total length of the primary group of barbs and in the length of their barbule-free tips. Two classes of barbs can be distinguished on the basis of overall length in feathers of any one of the tracts: (a) those barbs that form from the first group (complement) of 9-11 barb ridges that arise in strict dorsoventral order around the circumference of the epidermal cylinder strict dorsoventral order around the circumference of the epidermal cylinder of the feather germ, and (b) those barbs that are added secondarily, later, either by the formation of a newly organized ridge between the bases of two of the original group of barb ridges, or by the splitting of one or more of the original complement of barb ridges. The primary (majority) group of ridges, only, are of use in gauging tract specificity. The statistical significance of measurements of total barb-length and the length of the barbule-free tips have been evaluated; differences between the feathers of each of the seven tracts examined can be distinguished statistically. The fact that the first feathers to form from the papillae are tract-specific shows, unquestionably, that specificity is present in the papillae from the very beginning of their organization, as might be inferred from their orderly pattern of origin in time and space within each of the various tracts.