Signaling pathways and regulatory networks in quail skeletal muscle development: insights from whole transcriptome sequencing

Quail, as an advantageous avian model organism due to its compact size and short reproductive cycle, holds substantial potential for enhancing our understanding of skeletal muscle development. The quantity of skeletal muscle represents a vital economic trait in poultry production. Unraveling the molecular mechanisms governing quail skeletal muscle development is of paramount importance for optimizing meat and egg yield through selective breeding programs. However, a comprehensive characterization of the regulatory dynamics and molecular control underpinning quail skeletal muscle development remains elusive. In this study, through the application of HE staining on quail leg muscle sections, coupled with preceding fluorescence quantification PCR of markers indicative of skeletal muscle differentiation, we have delineated embryonic day 9 (E9) and embryonic day 14 (E14) as the start and ending points, respectively, of quail skeletal muscle differentiation. Then, we employed whole transcriptome sequencing to investigate the temporal expression profiles of leg muscles in quail embryos at the initiation of differentiation (E9) and upon completion of differentiation (E14). Our analysis revealed the expression patterns of 12,012 genes, 625 lncRNAs, 14,457 circRNAs, and 969 miRNAs in quail skeletal muscle samples. Differential expression analysis between the E14 and E9 groups uncovered 3,479 differentially expressed mRNAs, 124 lncRNAs, 292 circRNAs, and 154 miRNAs. Furthermore, enrichment analysis highlighted the heightened activity of signaling pathways related to skeletal muscle metabolism and intermuscular fat formation, such as the ECM-receptor interaction, focal adhesion, and PPAR signaling pathway during E14 skeletal muscle development. Conversely, the E9 stage exhibited a prevalence of pathways associated with myoblast proliferation, exemplified by cell cycle processes. Additionally, we constructed regulatory networks encompassing lncRNA‒mRNA, miRNA‒mRNA, lncRNA‒miRNA-mRNA, and circRNA-miRNA‒mRNA interactions, thus shedding light on their putative roles within quail skeletal muscle. Collectively, our findings illuminate the gene and non-coding RNA expression characteristics during quail skeletal muscle development, serving as a foundation for future investigations into the regulatory mechanisms governing non-coding RNA and quail skeletal muscle development in poultry production.

Glucose oxidation drives trunk neural crest cell development and fate

Bioenergetic metabolism is a key regulator of cellular function and signaling, but how it can instruct the behavior of cells and their fate during embryonic development remains largely unknown. Here, we investigated the role of glucose metabolism in the development of avian trunk neural crest cells (NCCs), a migratory stem cell population of the vertebrate embryo. We uncovered that trunk NCCs display glucose oxidation as a prominent metabolic phenotype, in contrast to what is seen for cranial NCCs, which instead rely on aerobic glycolysis. In addition, only one pathway downstream of glucose uptake is not sufficient for trunk NCC development. Indeed, glycolysis, mitochondrial respiration and the pentose phosphate pathway are all mobilized and integrated for the coordinated execution of diverse cellular programs, epithelial-to-mesenchymal transition, adhesion, locomotion, proliferation and differentiation, through regulation of specific gene expression. In the absence of glucose, the OXPHOS pathway fueled by pyruvate failed to promote trunk NCC adaptation to environmental stiffness, stemness maintenance and fate-decision making. These findings highlight the need for trunk NCCs to make the most of the glucose pathway potential to meet the high metabolic demands appropriate for their development.

Thymol feed supplementation in quail alters the percentages of nutritionally relevant egg yolk fatty acids: effects throughout incubation

BACKGROUND

Polyunsaturated fatty acids (PUFA) are crucial components of egg yolk and particularly prone to oxidative damage, generating losses of nutrients for embryonic development and influencing the quality of eggs for human consumption. The aim of this study was to evaluate whether dietary thymol (a natural antioxidant) is related to changes in quail egg yolk total (T), triglyceride (TG) and phospholipid (PL) fatty acid composition at different stages of embryo development. Thus female Japanese quail (100 days of age) were assigned to one of two dietary treatments (12 individuals each): CON (basal diet) or THY (0.0016 mol thymol day^-1 per bird). After 2 weeks of supplementation, eggs were incubated and samples were obtained at 0, 4 and 16 days of embryonic development.

RESULTS

In 0 day THY eggs, α-linolenic acid and n-3 PUFA in T and TG, docosahexaenoic acid and PUFA in T and arachidonic acid in TG were increased, while saturated fatty acids (SFA) in T were reduced. From 4 days on, PUFA, n-3 PUFA and SFA from T and TG in THY eggs were found to be similar to those of CON eggs. The changes in PL throughout incubation were similar in both dietary treatments.

CONCLUSION

Thymol would provide the embryo with PUFA for synthesis/deposition in membranes and/or assign to supply energy. Additionally, thymol supplementation would be advisable for the production of healthier table eggs. © 2017 Society of Chemical Industry.

Altered embryonic development in northern bobwhite quail (Colinus virginianus) induced by pre-incubation oscillatory thermal stresses mimicking global warming predictions

Global warming is likely to alter reproductive success of ground-nesting birds that lay eggs normally left unattended for days or even weeks before actual parental incubation, especially in already warm climates. The native North American bobwhite quail (Colinus virginianus) is such a species, and pre-incubation quail eggs may experience temperatures ≥45°C. Yet, almost nothing is known about embryonic survival after such high pre-incubation temperatures. Freshly laid bobwhite quail eggs were exposed during a 12 day pre-incubation period to one of five thermal regimes: low oscillating temperatures (25–40°C, mean = 28.9°C), high oscillating temperatures (30–45°C, mean = 33.9°C), low constant temperatures (28.85°C), high constant temperatures (mean = 33.9°C), or commercially employed pre-incubation temperatures (20°C). After treatment, eggs were then incubated at a standard 37.5°C to determine subsequent effects on embryonic development rate, survival, water loss, hatching, and embryonic oxygen consumption. Both quantity of heating degree hours during pre-incubation and specific thermal regime (oscillating vs. non-oscillating) profoundly affected important aspects of embryo survival and indices of development and growth Pre-incubation quail eggs showed a remarkable tolerance to constant high temperatures (up to 45°C), surviving for 4.5±0.3 days of subsequent incubation, but high oscillating pre-incubation temperature increased embryo survival (mean survival 12.2±1.8 days) and led to more rapid development than high constant temperature (maximum 38.5°C), even though both groups experienced the same total heating degree-hours. Oxygen consumption was ~200–300 μl O₂^.egg^.min^-1 at hatching in all groups, and was not affected by pre-incubation conditions. Oscillating temperatures, which are the norm for pre-incubation quail eggs in their natural habitat, thus enhanced survival at higher temperatures. However, a 5°C increase in pre-incubation temperature, which equates to the predicted long-term increases of 5°C or more, nonetheless reduced hatching rate by approximately 50%. Thus, while pre-incubation bobwhite eggs may be resiliant to moderate oscillating temperature increases, global warming will likely severely impact wild bobwhite quail populations, especially in their strongholds in southern latitudes.

The avian embryo as a model system for skeletal myogenesis

This review will focus on the use of the chicken and quail as model systems to analyze myogenesis and as such will emphasize the experimental approaches that are strongest in these systems-the amenability of the avian embryo to manipulation and in ovo observation. During somite differentiation, a wide spectrum of developmental processes occur such as cellular differentiation, migration, and fusion. Cell lineage studies combined with recent advancements in cell imaging allow these biological phenomena to be readily observed and hypotheses tested extremely rapidly-a strength that is restricted to the avian system. A clear weakness of the chicken in the past has been genetic approaches to modulate gene function. Recent advances in the electroporation of expression vectors, siRNA constructs, and use of tissue specific reporters have opened the door to increasingly sophisticated experiments that address questions of interest not only to the somite/muscle field in particular but also fundamental to biology in general. Importantly, an ever-growing body of evidence indicates that somite differentiation in birds is indistinguishable to that of mammals; therefore, these avian studies complement the complex genetic models of the mouse.

Fearfulness affects quail maternal care and subsequent offspring development

Our study investigated relationships between a precocial bird’s fearfulness and maternal care, and the implication of maternal care as a vector for non-genomic transmission of fearfulness to chicks. We compared care given to chicks between two sets of female Japanese quail selected to present either high (LTI) or low fearfulness (STI). Chicks, from a broiler line, were adopted by these females following a sensitization procedure. Chicks’ fearfulness after separation from their mother was assessed by well-established procedures. LTIs took longer to present maternal responses, pecked chicks more during the first days post-hatch, presented impaired maternal vocal behaviour and were globally less active than STI females. Chicks mothered by LTIs presented more fearful reactions than did chicks mothered by STIs, supporting the hypothesis of a non-genetic maternal transmission of fearfulness. We suggest that the longer latencies required by LTIs to become maternal are a consequence of their greater fear of chicks, and that their lower general and vocal activity could be components of a heightened antipredatory strategy. We discuss the transmission of maternal fearfulness to fostered chicks, taking into account the possible implication of several well-known mechanisms underlying maternal effects.

Morinda citrifolia L. leaf extract as antibacterial Salmonella typhimurium to increase productivity of quail (Coturnix coturnix japonica)

The objective of this study was to apply effect of Morinda citrifolia L. citrifolia L. leaf extract as antibacterial of Salmonella typhimurium on mortality of Day Old Quail (DOQ), egg production and Hen day, hatchability of layer quail. This research was conducted at Laboratory of microbiology and laboratory of poultry nutrition, faculty of animal science, bogor agricultural university and slamet quail farms cilangkap, sukabumi, west java, Indonesia on March-July 2012. Two hundred and forty heads of quail were randomly assigned to four dietary treatments (sixty heads of quail/treatment). Experimental design used was Completely Randomized Design (CRD). The treatments consist of level of biscuit Morinda citrifolia L. Citrifolia L. leaf extract i.e R1 = 0%, R2 = 5%, R3 = 10%, R4 = 15%. The results indicated the treatments had significant effect (p < 0.05) on mortality of Day Old Quail (DOQ). The average mortality of Day Old Quail (DOQ) was given extract Morinda citrifolia L. leaf were R1 (4.00%), R2 (1.00%), R3 (1.33%), R4 (0.67%). The average mortality of Day Old Quail (DOQ) was given 15% extract Morinda citrifolia L. leaf (R4) was lowest than control treatment (R1). The results of the analysis indicated that Morinda citrifolia L. leaf of quail drink had not significant effect (p > 0.05) on egg production, hen day and hatchability. It was concluded that the Morinda citrifolia L. leaf extract 15% can reduce mortality of Day Old Quail (DOQ) and can increase its egg production, hen day and hatchability.

Short- and long-term effects of unpredictable repeated negative stimuli on Japanese quail's fear of humans

Numerous aversive events occur in poultry production, and if repeated and unpredictable, can result in an impaired welfare. Some events such as handling can be perceived negatively and it is of interest to understand how humans' behaviour could affect poultry's behaviours and especially its avoidance of humans. Our aim was to evaluate short- and long-lasting effects of a 3-week procedure involving unpredictable repeated negative stimuli (URNS) applied during the post-juvenile period on quail's reactivity to humans. We compared the reactions of two sets of quail: URNS was applied to one set (treated quail) and the other set was left undisturbed (control quail). When two weeks old, treated quail were exposed to a variety of negative stimuli, either applied automatically or involving human presence. One and seven weeks after the termination of the procedure, the reactivity of control and treated quail to a passive human being was evaluated. Furthermore, the experimenter with her hand on a trough containing a mealworm assessed the propensity of quail of both groups to habituate to feed close to a human being. In the presence of a seated observer, treated quail were more inhibited and more alert than control quail. Likewise, seven weeks after the end of the URNS procedure, more treated than control quail adopted a fear posture. Moreover, whereas control quail spent as much time in the different areas of their cages, treated quail spent more time in the rear part of their cages. Finally, whereas control quail habituated gradually to feed near the experimenter's hand, treated quail did not. All these tests evidence negative short- and long-term effects on treated quail's reactivity to a passive human being and on their habituation to a human being when her presence is positively reinforced. This highlights the importance of young poultry's experience with humans in production.

Nuclear actin depolymerization in transcriptionally active avian and amphibian oocytes leads to collapse of intranuclear structures

Actin, which is normally depleted in the nuclei of somatic cells, accumulates in high amounts in giant nuclei of amphibian oocytes. The supramolecular organization and functions of this nuclear pool of actin in growing vertebrate oocyte are controversial. Here, we investigated the role of nuclear actin in the maintenance of the spatial architecture of intranuclear structures in avian and amphibian growing oocytes. A meshwork of filamentous actin was not detected in freshly isolated or fixed oocyte nuclei of Xenopus, chicken or quail. We found that the actin meshwork inside the oocyte nucleus could be induced by phalloidin treatment. Actin polymerization is demonstrated to be required to stabilize the specific spatial organization of nuclear structures in avian and amphibian growing oocytes. In experiments with the actin depolymerizing drugs cytochalasin D and latrunculin A, we showed that disassembly of nuclear actin polymers led to chromosome condensation and their transportation to a limited space within the oocyte nucleus. Experimentally induced "collapsing" of chromosomes and nuclear bodies, together with global inhibition of transcription, strongly resembled the process of karyosphere formation during oocyte growth.

3D reconstructions of quail-chick chimeras provide a new fate map of the avian scapula

Limbed vertebrates have functionally integrated postcranial axial and appendicular systems derived from two distinct populations of embryonic mesoderm. The axial skeletal elements arise from the paraxial somites, the appendicular skeleton and sternum arise from the somatic lateral plate mesoderm, and all of the muscles for both systems arise from the somites. Recent studies in amniotes demonstrate that the scapula has a mixed mesodermal origin. Here we determine the relative contribution of somitic and lateral plate mesoderm to the avian scapula from quail-chick chimeras. We generate 3D reconstructions of the grafted tissue in the host revealing a very different distribution of somitic cells in the scapula than previously reported. This novel 3D visualization of the cryptic border between somitic and lateral plate populations reveals the dynamics of musculoskeletal morphogenesis and demonstrates the importance of 3D visualization of chimera data. Reconstructions of chimeras make clear three significant contrasts with existing models of scapular development. First, the majority of the avian scapula is lateral plate derived and the somitic contribution to the scapular blade is significantly smaller than in previous models. Second, the segmentation of the somitic component of the blade is partially lost; and third, there are striking differences in growth rates between different tissues derived from the same somites that contribute to the structures of the cervical thoracic transition, including the scapula. These data call for the reassessment of theories on the development, homology, and evolution of the vertebrate scapula.

Quantitative and morphometric evaluation of the angiogenic effects of leptin

Angiogenesis is a dynamic process that requires an interaction of pro-and antiangiogenic factors. It is known that the cytokine leptin stimulates endothelial cell growth and angiogenesis, but further quantitative analysis is necessary to understand leptin angiogenic effects. The quail chorioallantoic membrane (CAM) assay has been used to study angiogenesis in vivo by focusing on morphometric parameters that quantify vascular complexity and density. We quantify the angiogenic activity of leptin using the CAM assay by digital morphometry and a computer-assisted image analysis to evaluate more precisely vessel length, diameter, branching, and tortuousity. CAM images are obtained from ex ovo cultures of E8-E9 quail embryos. MATLAB and custom software are used for our analysis. The effects of leptin, vascular endothelial growth factor-165 (VEGF(165)), and their corresponding neutralizing antibodies are compared. Our results show that CAM treated with leptin and VEGF(165) has a significant increase in vascular complexity and density. A corresponding decrease is observed using neutralizing antibodies. Notably, leptin induced more significant changes than VEGF in vessel length and tortuousity. Conversely, VEGF induced a greater increase in vessel branching than leptin. These results underscore the importance of using multiparametric quantitative methods to assess several aspects of angiogenesis and enable us to understand the proangiogenic effects of leptin.

[Effect of amaranth seed addition to ration of quails on lipid composition of the pancreas, skeletal muscles and egg's yolk]

A modifying effect is established of amaranth's corn on lipid composition of pancreas and skeletal muscles of quail - content of cholesterol goes down, the level of triacylglycerols and ethers of cholesterol rises, while the quantity of general lipids and correlation of their separate fractions in egg's yolk did not change substantially.

Cloacal Gland Growth Differences in High and Low Plasma Corticosterone Stress Response Line Male Quail Reared Under Short Daylengths

Mail quail selected (generation 32) for reduced [low stress (LS)] or exaggerated [high stress (HS)] plasma corticosterone stress response to brief mechanical restraint (5 min of immobilization) were studied for differences in the growth of their cloacal glands when reared essentially lifelong on short day lengths of 8L:16D. Post-brooding, at 4 wk of age, 96 quail (48 LS+48 HS) were housed in cages (1 LS and 1 HS male/cage), and the short day light treatment was instigated. Using a digital caliper, cloacal gland (CG) size measurements (length and width, mm) were made biweekly beginning at 42 d of age and ending at 196 d of age (28 wk old). The CG volume (CVOL) was calculated from these measurements using a literature-proposed formula. The CVOL in both lines increased similarly with increasing age from 6 to 12 wk of age. However, beginning at 14 wk of age and thereafter, LS males showed greater (P<0.05) CVOL than HS ones. No further increases in CVOL were observed in either line at 24 wk of age beyond that seen at 22 wk. This study demonstrated that although both lines show CG development under short days, eventually CG growth becomes comparatively stymied in the HS males. Furthermore, the maintenance of similarly lower CVOL in HS than LS males, CVOL that showed no further increase from 22 to 24 wk of age, suggests that holding these quail lifelong on short days results in, comparatively, yet another permanent negative reproductive consequence in quail selected for exaggerated plasma corticosterone stress responsiveness.

Vascular patterning of the quail coronary system during development

Recent studies have provided insights into specific events that contribute to vasculogenesis and angiogenesis in the developing coronary vasculature. This study focused on the developmental progression of coronary vascularization beginning with tube formation and ending with the establishment of a coronary arterial tree. We used electron microscopy, histology of serial sections, and immunohistochemistry in order to provide a comprehensive view of coronary vessel formation during the embryonic and fetal periods of the quail heart, a species that has been used in a number of studies addressing myocardial vascularization. Our data reveal features of progenitor cells and blood islands, tubular formation, and the anatomical relationship of a transformed periarterial tubular network and sympathetic ganglia to the emergence and branching of the right and left coronary arteries. We have traced the pattern of coronary artery branching and documented its innervation. Finally, our data include the relationship of fibronectin, laminin, and apoptosis to coronary artery growth. Our findings bring together morphological events that occur over the embryonic and fetal periods and provide a baseline for studies into the mechanisms that regulate the various events that occur during these time periods.

[Antioxidant status in tissue of the liver and pancreas of quails and its correction by adding the corn of amaranth to their feed]

The paper deals with the results of research of activity of enzymes of superoxide dismutase and catalase, and also amount of products of lipid peroxidation, in tissue of liver and pancreas of quails in the postnatal period of ontogenesis and their correction by the grinded corn of amaranth. It is established that the first weeks of quails life is distinguished by a deficiency of antioxidant system, and the corn of amaranth activates the enzymes of antioxidant defence, that favours a decrease in the content of lipid peroxidation products in the studied organs.

A comparative study of embryonic development of some bird species with different patterns of postnatal growth

Some studies show that birds with high postnatal growth rates (e.g. altricial species) are characterized by a rapid early development of "supply" organs, such as digestive organs. Birds with low postnatal growth rates (e.g. precocial species) exhibit a slower early development of these organs and a more rapid early development of other "demand" organs, such as brain, muscles, skeleton and feathers. To test whether these differences can be traced back to early embryonic development and whether they can be associated with changes in developmental timing, i.e. heterochrony, we compared embryos of the precocial quail and the altricial fieldfare, two bird species with low and high postnatal growth rates, respectively. We used classical staging techniques that use developmental landmarks to categorize embryonic maturity as well as morphological measurements. These techniques were combined with immune detection of muscle specific proteins in the somites. Our data showed that the anlagen of the head, brain and eyes develop earlier in the quail than in the fieldfare in contrast to the gut which develops earlier in the fieldfare than in the quail. Our data also showed that the quail and the fieldfare displayed different rates of myotome formation in the somites which contribute to muscle formation in the limbs and thorax. We believe these observations are connected with important differences in neonatal characteristics, such as the size of the brain, eyes, organs for locomotion and digestion. This leads us to the conclusion that selection for late ontogenetic characteristics can alter early embryonic development and that growth rate is of fundamental importance for the patterning of avian embryonic development. It also appears that this comparative system offers excellent opportunities to test hypotheses about heterochrony.

Morphogenesis of parrot jaw muscles: understanding the development of an evolutionary novelty

Parrots have developed novel head structures in their evolutionary history. The appearance of two new muscles for strong jaw adduction is especially fascinating in developmental and evolutionary contexts. However, jaw muscle development of parrots has not been described, despite its uniqueness. This report first presents the normal developmental stages of the cockatiel (Nymphicus hollandicus), comparable to that of the chick. Next, the peculiar skeletal myogenesis in the first visceral arch of parrots is described, mainly focusing on the development of two new jaw muscles. One of the parrot-specific muscles, M. ethmomandibularis, was initially detected at Nymphicus Stage 28 (N28) as the rostral budding of M. pterygoideus. After N32, the muscle significantly elongates rostrodorsally toward the interorbital septum, following a course lateral to the palatine bone. Another parrot-specific muscle, M. pseudomasseter, was first recognized at N36. The muscle branches off from the posteromedial M. adductor mandibulae externus and grows in a dorsolateral direction, almost covering the lateral surface of the jugal bar. The upper tip of the muscle is accompanied by condensed mesenchyme, which seems to be derived from cephalic neural crest cells.

A conserved role for retinoid signaling in vertebrate pancreas development

Retinoic acid (RA) signaling plays critical roles in the regionalization of the central nervous system and mesoderm of all vertebrates that have been examined. However, to date, a role for RA in pancreas and liver development has only been demonstrated for the teleost zebrafish. Here, we demonstrate that RA signaling is required for development of the pancreas but not the liver in the amphibian Xenopus laevis and the avian quail. We disrupted RA signaling in Xenopus tadpoles, using both a pharmacological and a dominant-negative strategy. RA-deficient quail embryos were obtained from hens with a dietary deficiency in vitamin A. In both species we found that pancreas development was dependent on RA signaling. Furthermore, treatment of Xenopus tadpoles with exogenous RA led to an expansion of the pancreatic field. By contrast, liver development was not perturbed by manipulation of RA signaling. Taken together with our previous finding that RA signaling is necessary and sufficient for zebrafish pancreas development, these data support the hypothesis that a critical role for RA signaling in pancreas development is a conserved feature of the vertebrates.

Histological preparation of developing vestibular otoconia for scanning electron microscopy

The unique nature of vestibular otoconia as calcium carbonate biominerals makes them particularly susceptible to chemical deformation during histological processing. We fixed and stored otoconia from all three otolith endorgans of embryonic, hatchling and adult Japanese quail in glutaraldehyde containing either phosphate or non-phosphate buffers for varying lengths of time and processed them for scanning electron microscopy. Otoconia from all age groups and otolith endorgans processed in 0.1 M phosphate buffer (pH 7.4) showed abnormal surface morphology when compared to acetone fixed controls. Otoconia processed in 0.1 M sodium cacodylate or HEPES buffered artificial endolymph (pH 7.4) showed normal morphology that was similar to controls. The degree of otoconial deformation was directly related to the time exposed to phosphate buffer. Short duration exposure produced particulate deformations while longer exposures resulted in fused otoconia that formed solid sheets. Otoconial surface deformation and fusing was independent of the glutaraldehyde component of the histological processing. These findings should help vestibular researchers to develop appropriate histological processing protocols in future studies of otoconia.

A novel role for retinoids in patterning the avian forebrain during presomite stages

Retinoids, and in particular retinoic acid (RA), are known to induce posterior fates in neural tissue. However, alterations in retinoid signalling dramatically affect anterior development. Previous reports have demonstrated a late role for retinoids in patterning craniofacial and forebrain structures, but an earlier role in anterior patterning is not well understood. We show that enzymes involved in synthesizing retinoids are expressed in the avian hypoblast and in tissues directly involved in head patterning, such as anterior definitive endoderm and prechordal mesendoderm. We found that in the vitamin A-deficient (VAD) quail model, which lacks biologically active RA from the first stages of development, anterior endodermal markers such as Bmp2, Bmp7, Hex and the Wnt antagonist crescent are affected during early gastrulation. Furthermore, prechordal mesendodermal and prospective ventral telencephalic markers are expanded posteriorly, Shh expression in the axial mesoderm is reduced, and Bmp2 and Bmp7 are abnormally expressed in the ventral midline of the neural tube. At early somite stages, VAD embryos have increased cell death in ventral neuroectoderm and foregut endoderm, but normal cranial neural crest production, whereas at later stages extensive apoptosis occurs in head mesenchyme and ventral neuroectoderm. As a result, VAD embryos end up with a single and reduced telencephalic vesicle and an abnormally patterned diencephalon. Therefore, we propose that retinoids have a dual role in patterning the anterior forebrain during development. During early gastrulation, RA acts in anterior endodermal cells to modulate the anteroposterior (AP) positional identity of prechordal mesendodermal inductive signals to the overlying neuroectoderm. Later on, at neural pore closure, RA is required for patterning of the mesenchyme of the frontonasal process and the forebrain by modulating signalling molecules involved in craniofacial morphogenesis.

A comparative study of neurogenesis in the retinal ciliary marginal zone of homeothermic vertebrates

The retina of many fish and amphibians grows throughout life, roughly matching the overall growth of the animal. The new retinal cells are continually added at the anterior margin of the retina, in a circumferential zone of cells, known as the ciliary marginal zone, or CMZ. Recently, Fischer and Reh [Dev. Biol. 220 (2000) 197] have found that new neurons are added to the retina of the chicken via proliferation and subsequent differentiation of neurons and glia at the retinal margin in a zone highly reminiscent of the CMZ of lower vertebrates. In addition, other groups have reported that putative retinal stem cells could be isolated from the ciliary margin of the adult mouse. In light of these findings, we have re-investigated the eyes of three additional species to determine whether other homeothermic vertebrates also possess CMZ cells and whether we could detect evidence for addition of neurons at the retinal margin in mature animals. We examined one additional avian species, the quail, one marsupial, the opposum, and one mammal, the mouse. We find that the CMZ cells have been gradually diminished during vertebrate evolution. The quail has a reduced CMZ as compared to the chicken, while the opposum has only a few cells likely related to the CMZ and we failed to find evidence of CMZ cells at the margin of the mouse retina.

D1-receptor dependent synaptic potentiation in the basal ganglia of quail chicks

Properties of local synapses were analyzed in lobus parolfactorius (LPO; avian homologue of caudate-nucleus) of quail chicks by using slice preparations in vitro. Field-potential extracellular and whole-cell intracellular recordings revealed excitatory synaptic inputs converging from dorsal and ventral regions within LPO. With exogenous dopamine (100 microM) in the perfusate, synchronized conditioning stimulation induced biased changes in the dorsal and the ventral inputs; potentiation in the dorsal input and depression in the ventral input in average. On the other hand, de-synchronized conditioning failed to induce such biased changes, although the differences were not statistically significant. SCH-23390 (3 microM) blocked the dorsal potentiation, while AP-5 (100 microM) tended to block both of these changes. The plastic nature may underlie the memory formation in appetitive/aversive learning tasks.

Developmental changes in galanin in lumbosacral sympathetic ganglionic neurons innervating the avian uterine oviduct and galanin induction by sex steroids

We recently found lumbosacral sympathetic ganglionic galanin neurons innervating the quail uterine oviduct. Galaninergic innervation of the uterine muscle may be essential for avian oviposition, as galanin evoked oviposition through a mechanism of induction of vigorous uterine contraction. The questions arising from these findings are: what changes occur in galanin expression in the sympathetic ganglionic galanin neuron during development, and what is the hormonal factor(s) that induces galanin expression in this neuron? Therefore, the present study examined the developmental changes in galanin of the quail sympathetic ganglionic neuron and uterus, and the effect of administration of ovarian sex steroids on galanin induction. Immature birds reared under long-day photoperiods from 4 weeks of age demonstrated progressive increases in galanin levels both per unit ganglionic protein (concentration) and per ganglia (content) concurrent with ganglionic development during weeks 4--13. The uterine galanin content and uterine weight also increased progressively during the same period, but the galanin concentration in the uterus at 4 weeks was high due to the much smaller tissue mass. Immunocytochemical analysis with anti-galanin serum showed that immunoreactive ganglionic cells were few and small at 4 weeks and increased progressively thereafter. Administration of oestradiol-17 beta to immature birds at 3 weeks of age for 1 week increased both the galanin concentration and content in the ganglia without ganglionic growth. A marked increase in galanin-immunoreactive ganglionic cells was detected following oestradiol treatment. In contrast, progesterone increased ganglionic galanin levels, but the effects were low. Expression of the mRNAs encoding oestrogen receptor-alpha and -beta (ER alpha and ER beta) in the ganglionic tissue was verified by RT-PCR/Southern blot analysis. Immunocytochemical staining with anti-ER serum further revealed an intense immunoreaction restricted to the nucleus of ganglionic neurons. These results suggest that ovarian sex steroids, in particular oestradiol-17 beta, contribute as hormonal factors to galanin induction, which takes place in the lumbosacral sympathetic ganglionic neurons innervating avian uterine oviduct during development. Oestradiol may act directly on this ganglionic neuron through intra-nuclear receptor-mediated mechanisms to induce galanin.

Development of microglia in the quail optic tectum

The development of microglia in the quail optic tectum from embryonic day 6 to adulthood was studied by using the QH1 monoclonal antibody. In youngest tecta, microglial cells were scarcely present, but their number rose in subsequent stages. A clear pattern of microglial cell distribution was observable in embryos of 9-16 days. (1) Round cells appeared close to the ventricular layer. (2) Large numbers of ameboid and round labeled cells were seen in the stratum album centrale during development. A gradient of cell density was observable in this layer, as fewer labeled cells appeared in medial regions of the tectum than in lateral regions. (3) Maturing ramified cells were found in layers external to the stratum album centrale, where they increased in number and in branching complexity during development. In adult tecta, almost all microglial cells were of the mature ramified type and were distributed homogeneously in the different tectal layers, although in some layers they had particular morphological features. The distribution of microglia in the developing tectum and in adjacent regions provided insight into the routes of microglial cell invasion of the tectum during development. Apparently, a proportion of microglial cells reached the tectal parenchyma from the meninges and from the ventricular lumen, but the majority of them migrated along nerve fiber tracts from their entry point at the pial surface of the ventromedial caudal tectum. After they reached the stratum album centrale, microglial cells continued their migration toward more external layers, where they differentiated into ramified microglia.

Evolution of acetylcholinesterase transcripts and molecular forms during development in the central nervous system of the quail

We studied the expression of acetylcholinesterase (AChE) in the nervous system (cerebellum, optic lobes and neuroretina) of the quail at different stages of development, from embryonic day 10 (E10) to the adult. Analyzing AChE mRNAs and AChE molecular forms, we observed variations in the following: (a) production of multiple mRNA species (4.5 kb, 5.3 kb, and 6 kb); (b) translation and/or stability of the AChE protein; (c) production of active and inactive AChE molecules; (d) production of amphiphilic and nonamphiphilic AChE forms; and (e) proportions of tetrameric G4, dimeric G2, and monomeric G1 forms. The large transcripts present distinct temporal patterns and disappear in the adult, which possesses only the 4.5-kb mRNA; these changes are unlikely to be related to those observed for the AChE protein, because all transcripts seem to encode the same catalytic subunit (type T). In addition, the levels of mRNA and AChE are not correlated in the three regions, especially at the adult stage. The proportion of inactive AChE was found to be markedly higher at the hatching period (E16) than at earlier stages (E10 and E13) or in the adult. The G4 form is predominant already at E10, and in the adult its proportion reaches 80% of the activity in the cerebellum and optic lobes, and 65-70% in the neuroretina. This form is largely nonamphiphilic in embryonic tissues, but it becomes progressively more amphiphilic with development. Thus, the different processing and maturation steps appear to be regulated in an independent manner and potentially correspond to physiologically adaptative mechanisms.

Biopotency of methionine sources and their effects on sexual maturity of growing Japanese quail

1. Japanese quail were fed on practical diets supplemented with graded amounts of DL-methionine (DL-M), DL-methionine-sodium (DL-M-Na), DL-methionine hydroxy-analogue calcium (DL-MHA-Ca) and DL-methionine hydroxy-analogue free acid (DL-MHA-FA) on an equimolar basis. 2. By the slope ratio assay using quail growth as the criterion, it was deduced that the biological activity of DL-M-Na, DL-MHA-Ca and DL-MHA-FA was approximately 0.96, 0.72 and 0.84 that of DL-M on an equimolar basis. 3. On a weight basis of the commercial products, the efficacies of DL-M-Na, DL-MHA-Ca and DL-MHA-FA were 0.38, 0.62 and 0.74, respectively. 4. Quail fed on the diet with the highest content of methionine had greater ovary weight, oviduct weight, oviduct length and egg production.

The nutritional value of dehydrated, blue-green algae (Spirulina platensis) for poultry

Three experiments were conducted to evaluate the nutritional value of the blue-green algae, Spirulina platensis, grown on a synthetic media. In Experiment 1, day-old, White Leghorn cockerel chicks (120) were fed isonitrogenous diets containing 0, 5, 10, 15, and 20% of dried spirulina. At 3 wk of age, the growth of the chicks fed 10 and 20% of spirulina was depressed (P less than .05), although feed efficiency was not affected. In Experiment 2, 250 1-day-old, Hubbard by Hubbard, male broiler chicks were fed experimental diets containing 0, 1.5, 3.0, 6.0, or 12.0% of spirulina for 41 days. Although the growth of the chicks fed the spirulina diets was not different from that of the chicks receiving the control diet, the birds receiving the 12% spirulina diet grew slower (P less than .05) than the chicks fed all of the other spirulina diets. In Experiment 3, 600 1-wk-old, Japanese qual were used to study the effects of 0, 1.5, 3.0, 6.0, and 12.0% of spirulina on growth, egg production, egg quality, fertility, hatchability, and the growth of the F1 generation of dams fed Spirulina. There were no significant differences due to the spirulina content in any of the parameters studied-except for yolk color, which increased with each succeeding level of spirulina, and for fertility, which was higher for all spirulina treatments versus the control.

Growth response to chronic beta agonist feeding and mature carcass characteristics of quail (Coturnix coturnix japonica) selected for high and low body densities

A study was conducted to determine the effect of long-term feeding of a beta agonist (cimaterol) on female Japanese quail. Quail used were from lines selected for high (HD) and low (LD) body density from a randombred population. Dietary treatments consisted of 1) the basal feed, 2) the basal feed containing .5 ppm, or 3) 1.0 ppm of the beta agonist. The treatment period for the six experimental groups extended from 14 to 94 days of age. Weight gains to 49 days and live weights at 94 days of age were greater (P less than .05) in the cimaterol-fed groups. Age and live weight at first egg in both lines were greater (P less than .01) when groups were fed treated diets. Eviscerated carcass yields were higher (P less than .01) and carcass moisture was lower (P less than .05) in treated groups. There were no differences in carcass fat or protein among the dietary treatments. Abdominal fat pad weights were larger (P less than .05) in the heavier (P less than .01) HD line but were not significantly affected by cimaterol. Abdominal adipocyte diameters were significantly larger in HD (P less than .05) and cimaterol-treated (P less than .05) quail.

Chick mortality in bobwhite quail as affected by supplemental ascorbic acid

In two experiments, bobwhite quail chicks were given 0, 50, or 500 ppm ascorbic acid (AA) in the drinking water from 1 to 7 days of age. Both levels of AA significantly decreased mortality for the first 7 days and for the 3-wk average. Feed conversion during the entire 3-wk study was improved by 500 ppm AA. Body weight was not affected by AA supplementation.

Aging and sex-related changes in the outer retina of Japanese quail

Age-related changes in the outer retina of Japanese quail 3 months to 3 years of age have been assessed with light and electron microscopy. A major difference was observed between males and females in the accumulation of lipofuscin in retinal pigment epithelial (RPE) cells. Females showed greater densities of lipofuscin granules, larger granules, and more lipofuscin per RPE cell than did males of comparable ages. In addition, a small but significant decrease (14-16%) in photoreceptor nuclear densities occurred in the temporal retina of both 1-year females and 3-year males. An overall correlation of -.77 between photoreceptor densities and amount of lipofuscin was observed, with a correlation of -.88 for females, alone. No male/female differences were observed with regard to age-related changes in height of RPE cells. Major differences in calcium metabolism and demand associated with egg-laying in females may underlie the observed sex-related differences that occur in the outer retina of this relatively short-lived, domestic species.

Divergent selection for growth in Japanese quail under split and complete nutritional environments. 2. Water and feed intake patterns and abdominal fat and carcass lipid characteristics

A study was conducted to investigate water and feed intake patterns, abdominal fat and carcass lipid levels, feed efficiency and growth in high (H) and low (L) body weight lines of Japanese quail divergently selected under complete diet (CD) or split diet (SD) environments. Birds under the SD environment could self-select from high-protein low-energy or low-protein high-energy diets. Progeny from both the selected and control (C) lines were evaluated under the SD environment in Generations 6 and 10, and under the CD environment in Generation 10. Under the SD environment, body weights of the H lines were similar as were body weights of the L lines; however, under the CD environment, there were significant differences between H lines and between L lines. Body weights were higher under the CD than under the SD environment. Differences between H and L lines in body weights and 1-wk relative growth rates within SD and CD environments were attributed to differences in water and feed consumption and feed efficiency. Water consumption was greater in the SD than CD environments. Feed consumption was greater in the SD than CD environment from 0 to 2 wk of age; thereafter, feed consumption was higher in the CD environment. Abdominal fat and carcass lipid levels were greater in H than L lines, with the magnitude of the difference greater in the SD environment, indicating that the SD may be a better environment than the CD environment for the study of abdominal fat and carcass lipids in Japanese quail.

Changes in serum concentrations of steroids during embryonic and post-hatching development of male and female Japanese quail (Coturnix coturnix japonica)

Serum concentrations of testosterone, 5 alpha-dihydrotestosterone, oestradiol and progesterone were measured by radioimmunoassay combined with Celite chromatography in male and female Japanese quail (Coturnix coturnix japonica) during the second half of embryonic life (days 9-17 of incubation) and during the first 5 weeks after hatching. The mean level of each of the four steroids was significantly affected by the age of the birds. An overall effect of sex was detected by analysis of variance only on oestradiol concentrations, with females having higher serum concentrations than males during most of the age range studied. Significant peaks of testosterone and progesterone were also detected around hatching time. These results are consistent with the view that oestradiol is the major hormone implicated in the sexual differentiation of reproductive behaviour in the quail. The relationships between the circulating concentrations of oestradiol during ontogeny and the critical period of differentiation as postulated by currently accepted models is also discussed.

Development of thyroid function and its pituitary control in embryonic and hatchling precocial Japanese quail and altricial Ring doves

We compared the developmental pattern of thyroid function and its pituitary control in precocial Japanese quail and altricial Ring doves. We measured thyroid hormone (TH) content of thyroid glands (TG), TH concentrations in the serum, relative pituitary gland thyrotropin (PG-TSH) content, and the ability of the TG to respond to exogenous TSH as indicated by increases in TG-3',5'-monophosphate (cAMP) content or in serum TH concentrations. In embryonic quail there is considerable maturation of thyroid function prior to hatching. TG-TH content is low but detectable in Day 8 embryos; TG-TH content increases 300x between Day 8 and hatching (16.5-day incubation). Pituitary TSH is detectable by bioassay in quail on embryonic Day 8, with higher levels found closer to hatching. The TG of 8-day embryos responds to TSH injection by increased TG-cAMP content but the serum TH response to TSH does not appear until Day 9. Serum TH concentrations suggest that the TG is under pituitary control during the latter part of incubation. In doves most of the development of thyroid function and the maturation of its pituitary control occur after hatching and thus thyroid functional development is much later in doves than in quail. TG-TH content is extremely low in embryos and nestlings up to 3 days after hatching, increases slowly in nestlings up to Day 10, then increases sharply. Serum TH content is very low in embryos and rises steadily in nestlings to plateau after about Day 8. Pituitary TSH content, estimated by a quail bioassay, is undetectable in embryos and nestlings until Day 4 but increases thereafter. The TG does not respond (based on serum TH concentration) to TSH injection through the day of hatching (Day 16; mean incubation period of 16.5 days), but an increase in serum TH occurs in Day 2 nestlings in response to TSH injection. The magnitude of this response continues to increase during the first week after hatching.

Divergent selection for growth in Japanese quail under split and complete nutritional environments. 1. Genetic and correlated responses to selection

Japanese quail were divergently selected for 4-wk body weight under two different nutritional environments. In one environment quail were divergently selected for high and low body weight (H and L) under a split diet (SD) with quail having the opportunity to self-select feed from high protein and high energy diets. In the other environment, quail were similarly selected (H and L) under a normal (28% protein) complete diet (CD). After 11 generations of selection, H-SD and H-CD lines were 48.9 and 49.7% higher in 4-wk body weight than controls. Quail from L-SD and L-CD lines were 46.5 and 45.4% lower in 4-wk body weight than controls. Realized heritabilities for 4-wk body weight were .36 +/- .03, .30 +/- .03, .52 +/- .02, and .47 +/- .03 for H-SD, L-SD, H-CD, and L-CD lines, respectively. Selection differentials were significantly higher in the SD than in the CD environment. Changes in 2-wk, adult body, and egg weight across generations paralleled that of the trait under selection (4-wk body weight). Selection also resulted in decreased hatchability and egg production with increased age to sexual maturity in both environments. The SD environment was determined to be a stress environment because of birds' inferior growth there compared with growth in the CD environment. Rate of growth, however, to reach adult body size was superior for L-SD quail once the stress environment was removed. There was also evidence that eggs were larger for quail in the SD than the CD environment.

Effects of dietary butylated hydroxyanisole and cysteine on toxicity of Lathyrus odoratus to broiler and Japanese quail chicks

The effect of .75% dietary butylated hydroxyanisole (BHA) and 1% cysteine on the toxicity of Lathyrus odoratus seed to Japanese quail and broiler chicks was examined. In both species, the feeding of Lathyrus seed as a component of a complete diet depressed (P less than .05) body weight gain and feed intake. Typical signs of lathyrism, including ruffled feathers, enlarged hocks, curled toes, ataxia, leg paralysis, and mortality, were observed. Neither BHA nor cysteine exerted protective effects against the lathyrogenic effects. As assessed by mortality, these additives appeared instead to potentiate Lathyrus toxicity.

Effects of oestrogen and anti-oestrogen on the cells of the endosteal surface of male Japanese quail

1. The endosteal cellular response occurring in the early stages of medullary bone formation was histologically examined in the femurs of male Japanese quail treated with oestrogen and antioestrogen. 2. The numbers of endosteal cells decreased, and preosteoblasts and osteoblasts increased, on the endosteal surface following oestrogen treatment. 3. After oestrogen and anti-oestrogen treatment the numbers of preosteoblasts and osteoblasts on the endosteal surface did not increase. However, endosteal cells slowly decreased in number and osteoclasts increased. 4. This study demonstrates that differentiation of osteoblasts is induced by oestrogen stimulation and suggests that osteoclasts occur by oestrogen inhibition on the endosteal surface.

Growth hormone status and growth characteristics of Japanese quail divergently selected for four-week body weights

A randombred line of quail (R1) and two lines selected for either increased (HW) or decreased (LW) 4-wk body weight were used to examine the relationship of growth to circulating growth hormone (GH) levels during growth. Differences in GH between males and females were not detected. Growth hormone was low at hatching in all lines but then increased to relatively high levels by the first post-hatching sample (3 to 7 days). A decline in GH then occurred in all lines, with low adult levels detected earlier in lines HW and R1 than in LW. The patterns of GH secretion and growth characteristics of lines HW and R1 were similar while those of LW were unique.

Response of growth-selected Japanese quail lines to tannin levels in grain sorghum diets with suboptimal protein

Growth of selected lines of Japanese quail fed grain sorghum diets was evaluated. Suboptimal protein levels (23 and 25%) were used in conjunction with two varieties of sorghum differing in tannin content (.02 vs. 6.06%). Chicks of three related lines of quail differing in growth rates and mature body sizes were fed the diets from 0 to 28 days of age. Growth was significantly reduced (14 and 6%) by substitution of high tannin sorghum for low tannin sorghum in the 23 and 25% protein diets, respectively. No line X diet interaction was observed.

Influence of 12 hours of sound stimuli on gonad development and plasma luteinizing hormone in Japanese quail (Coturnix coturnix japonica) exposed to 6 hours of daily light

Two experiments were conducted to determine the effects of sound stimulation on gonadal growth in male and female Japanese quail (Coturnix coturnix japonica) maintained under a photoperiod of 6 hr light and 18 hr dark (6L:18D) from 1 to 12 weeks of age (Experiment 1) or 1 to 14 weeks of age (Experiment 2). The quail were split into three sound environments as follows: 1) 12 hr of radio music (RS) beginning 1 hr before lights off; 2) 12 hr of vocalization from a breeding colony of quail (QV) beginning 1 hr before lights off; 3) no sound stimulation (NS). In Experiment 1, birds were killed at 8, 10, and 12 weeks of age and in Experiment 2, they were killed at 8, 10, 12, and 14 weeks of age. There were no significant differences in tests weights of the three groups at 8 and 10 wk of age (Experiment 1), but those of the RS and QV groups were larger (P less than or equal to .05) than those of the NS group at 12 weeks. Tests in the NS group appeared to grow between 8 and 10 weeks, then regress. There were no differences in testis weights at 8 and 10 weeks of age in Experiment 2. At 12 weeks, testes in the RS group were larger (P less than or equal to .05) than those of the other two groups and by 14 weeks testes of both sound stimulated groups were larger than the NS group and were also different from each other.(ABSTRACT TRUNCATED AT 250 WORDS)

Developmental changes induced by glucocorticoids treatment in breeder quail (Coturnix coturnix japonica)

The effects produced in offspring by corticosterone treatment to breeder quail were investigated. The breeders received corticosterone orally every day during 7 days. The total dose administered was 3.15 mg/quail/7 days. The quail from treated breeders have a decreased rate of body growth during the experimental period. The studied metabolic and nutritives parameters were smaller than the control group, however, the relative indices were similar. The breeders treated with corticosterone produce quail smaller than controls, but the pattern during the growth period is similar, there it can be observed by the same relative indices.

Changes in the blood and the bone marrow picture of the Pharaoh quail (Coturnix coturnix Pharaoh) chicks as a manifestation of adaptation to postembryonal life

1. The aim was determination of the rate of adaptation of the respiratory and defence functions of the blood and bone marrow of quail chicks. 2. In the early post-hatching period, enhanced haemoglobin synthesis is the mechanism adapting the bird to the rich oxygen conditions beyond the egg. 3. In 2-week-old chicks, the increased respiratory function of the blood is associated with a parallel rise of the erythrocyte count and haemoglobin content. 4. The defence mechanisms of the chick in the first days after hatching are mainly connected with a high content of heterophilic granulocytes and in older chicks with a rising lymphocyte count.

Oral and intramuscular toxicity of inorganic and organic mercury chloride to growing quail

The lethal toxicity of inorganic (HgCl2) and organic (CH3HgCl) mercury chloride was compared for Coturnix (Japanese quail, Coturnix japonica) of different ages from hatch through adulthood by single-dose acute oral and intramuscular injections and by a 5-d dietary trial. Sublethal mercury toxicity was studied by evaluation of plasma and brain cholinesterase activity. CH3HgCl was more toxic than HgCl2 in all tests at each age tested. LD50s consistently increased over the first 4 wk for both acute methods and both mercurials and then stabilized. The striking difference between single-dose acute and 5-d dietary tests was that CH3HgCl averaged about twice as toxic as HgCl2 by both acute methods, compared to 100 times as toxic by the dietary method. For example, at 2 wk of age, the oral LD50s for CH3HgCl and HgCl2 were 18 and 42 mg/kg and the dietary LC50s were 47 and 5086 ppm. When birds were fed HgCl2 and developed clinical signs of intoxication, they could recover once treatment was withdrawn; however, on CH3HgCl, clinical signs often commenced after treatment was withdrawn, and then actually intensified for several days and culminated in death.

Magnum morphogenesis during the natural development of the quail oviduct: analysis of egg white proteins and progesterone receptor concentration

The histological development of the quail oviduct and the changes in concentrations of progesterone receptor, ovalbumin, conalbumin, ovomucoid and ovoglycocomponents are analyzed during the period spanning 7-35 days of age. The initiation of luminal epithelial cell proliferation is the first event of magnum growth. The epithelial cells begin to evaginate into subepithelial stroma and form tubular glands. Meanwhile, luminal epithelium starts cellular pleomorphism through ciliogenesis. No egg white proteins are detectable in the developing glands; at the same time, the concentration of the progesterone receptor increases from about 5500 sites/cell to 30,300 sites/cell. Tubular gland cells then begin to synthetize and accumulate egg white proteins, mucous cells differentiate in the luminal epithelium, and the cell proliferation decreases and finally stops. Compared with earlier studies dealing with the blood levels of estrogen and progesterone in developing quails during the same period, and the cellular changes induced in the oviducts of ovariectomized and ovariectomized-hypophysectomized quail by exogenous steroids, these results distinguish between the cellular responses that are physiologically controlled by estradiol and other responses that have multihormonal regulation.

Testosterone induces hypothalamic aromatase during early development in quail

The effects of testosterone on androgen metabolizing enzymes were examined in the developing hypothalamus of male and female quail using an in vitro radiometric assay which measures metabolite formation in individual brain samples. Testosterone (T) administered by subcutaneous silastic implants to gonadectomized 4-day-old chicks increased formation of estradiol-17 beta (E2) in both preoptic area + anterior hypothalamus (PA) and posterior hypothalamus + tuberal area (HT) to adult levels. The T-induced increase in E2 formation occurred to the same degree in both sexes. The increase was very small in control non-target areas, neostriatum intermediale + hyperstriatum ventrale (VN), of either sex. Testosterone had no effect on formation of 5 alpha-dihydrotestosterone (5 alpha-DHT), 5 beta-dihydrotestosterone (5 beta-DHT) and 5 beta-androstane 3 alpha, 17 beta-diol (5 beta, 3 alpha-diol) in PA. Kinetic analysis of the rate of E2 production by hypothalamic tissue from castrated chicks (CX-chicks) and castrates treated with T (CX + T-chicks) indicates that the increase in hypothalamic aromatase activity by T corresponds to induction of the enzyme: the Vmax (maximum velocity) was increased by T (CX-chicks, 21; CX + T-chicks, 91 fmol/mg FW/h), whereas the Km was unaffected (CX-chicks, 5.5; CX + T-chicks, 4.7 X 10(-8) M). Testosterone treatment, effective for inducing PA and HT aromatase activity, also activated crowing and caused cloacal gland development; neither of these effects were sexually dimorphic. Our results indicate that: (1) T induces aromatase specifically in the hypothalamus during early post-hatching development, other pathways of T metabolism are not affected; and (2) the inducible aromatase is not sexually dimorphic in the developing brain. Since there are sex differences in adult brain aromatase, we conclude that capacity for induction of the hypothalamic aromatase becomes sexually differentiated after the post-hatching period.

Postnatal development of a demyelinating disease in avian spinal cord chimeras

Xenogeneic spinal cord chimeras were constructed by grafting fragments of quail neural primordium into chick embryos at 2 days of incubation. Hatched birds displayed normal motor behavior for about 5 to 7 weeks, whereupon they developed a neurological syndrome; in the grafted spinal cord the pathological signs of the disease were very similar to those of the active plaques of multiple sclerosis and of the lesions of experimental allergic encephalomyelitis and neuritis, including Ia expression by brain capillary endothelia, rupture of the blood-brain barrier, leukocytic infiltration in the nervous tissue, and demyelination. In the animals at the most advanced stage of the disease an autoimmune attack occurred on the host's nervous system with the same histopathological signs.

[Viability of embryos and nestlings after the exposure of quail eggs to gamma-radiation and vibration at various times during egg storage]

The viability of quail embryos and nestlings from the incubation eggs exposed (in) to gamma-radiation at a dose of 300 cGy and stored for 15 days or (ii) to gamma-radiation at a dose of 300 cGy and stored for 30 days or (iii) to vibration with the acute egg end oriented contrary to the vibration front and stored for 30 days did not decrease as compared to that of the controls stored for the same time period. The viability diminished if the radiation dose was increased to 600-1200 cGy of if the egg orientation during vibration was changed.

Survey of vitamin D metabolite levels during growth and development in Japanese quail

Plasma calcium and vitamin D metabolite levels were monitored during growth and development in male and female Japanese quail. In male Japanese quail, plasma calcium levels were constant (range 9.0 to 10.9 mg/dl); the 1,25-dihydroxyvitamin D [1,25-(OH)2D] levels remained undetectable in all age groups. Plasma calcium levels in the females rose at 6 weeks of age and remained elevated. The female 1,25-(OH)2D levels increased from undetectable levels at 3 to 5 weeks to a peak of 297 pg/ml at 8 weeks and remained elevated at 12 weeks of age in ovulating birds. Twelve-week old female without an egg in their oviduct had plasma 1,25-(OH)2D levels similar to males and immature females. No marked changed occurred in plasma 25-(OH)D levels due to sex or age. Plasma 24, 25-(OH)2D levels stayed relatively constant at about 2 ng/ml for both male and females at all ages studied.

Free thyroid hormones in altricial (ring doves) versus precocial (Japanese quail) development

Ring doves (altricial development) and Japanese quail (precocial development) were used as models to compare differences in serum free hormone concentrations and the binding of thyroid hormones to serum protein fractions in adults, and the pattern of free thyroid hormones in the serum of altricial vs. precocial young. Total and free hormones were determined directly by RIA; free hormones also were determined by equilibrium dialysis. Binding protein fractions were identified by electrophoresis of serum preincubated with labelel hormones. Albumin bound the largest proportion of T4 in serum to both species; albumin also bound the largest proportion of T3 in doves, but globulin bound the largest proportion in quail. There were significant differences between species in the proportional binding of both thyroid hormones by different protein fractions at physiological pH. Electrophoretic separations at alkaline pH significantly altered hormone binding by different protein fractions from that at physiological pH. These data explain some conflicting results in the literature on thyroid hormone-binding proteins in different species. Free T4 and free T3 were below the sensitivity limits of the assays during the perinatal period in doves. After hatching, serum free T4 rose more rapidly than total T4. After day 12, hormone concentrations decreased, with a proportionately greater change in free T4 than in total T4. Serum free T3 concentrations were variable, but did not change significantly during development. These results demonstrate that the pattern of serum free thyroid hormones, like that of total hormones, is markedly different in altricial than in precocial development.