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Metabolic coupling of glutathione between mouse and quail cardiac myocytes and its protective role against oxidative stress.

Cultured quail myocytes were much more resistant to H2O2 toxicity than cultured mouse myocytes. The intracellular concentration of glutathione ([GSH]i) and the activity of gamma-glutamylcysteine synthetase (gamma-GCS) in quail heart cells were about five and three times higher, respectively, than in mouse heart cells, although catalase and glutathione peroxidase (GSHpx) activity was similar in both. Preloading of gamma-glutamylcysteine monoethyl ester (gamma-GCE), a membrane-permeating GSH precursor, increased the H2O2 resistance of cultured mouse myocytes. These observations suggest that the high [GSH]i and the high activity of gamma-GCS in quail myocytes are responsible for their high resistance to H2O2. Both H2O2 sensitivity and [GSH]i of mosaic sheets composed of equal amounts of mouse and quail myocytes approximated those of sheets composed entirely of quail myocytes. From these observations, it is hypothesized that GSH was transferred from quail myocytes to mouse myocytes, probably through gap junctions between them, and that quail myocytes resynthesized GSH by a feedback mechanism, thus maintaining their intracellular GSH levels. When the fluorescent dye lucifer yellow was injected into a beating quail myocyte in a mosaic sheet, it spread to neighboring mouse myocytes but not to neighboring L cells (a cell line derived from mouse connective tissue). These observations indicate that existence of gap junctions in the region of cell contact between mouse and quail myocytes but not between quail myocytes and L cells. When quail myocytes preloaded with [3H]gamma-GCE were cocultured with mouse myocytes and L cells, the radioactivity was transmitted to neighboring mouse myocytes but not L cells. These observations show that GSH and/or its precursors can be transmitted from quail myocytes to mouse myocytes through gap junctions and that this can protect mouse myocytes from H2O2 toxicity. Mouse myocyte sheets composed of 10(4) cells or more showed higher resistance to H2O2 toxicity than single isolated mouse myocytes. Metabolic coupling of GSH between myocytes may contribute at least in part to this high resistance of the cell sheets.

Animals↗

Growth of murine sarcoma and murine xenotropic leukemia viruses in Japanese quail: induction of tumors and development of continuous tumor cell lines.

The BALB/c murine endogenous xenotropic leukemia virus pseudotype of m1 Moloney sarcoma virus [m1MSV(B-MuX)] was used to productively transform diploid Japanese quail embryo cells. The majority of newly hatched quail inoculated with m1MSV(B-MuX)-transformed quail embryo fibroblast cells rapidly developed tumors which were predominantly locally invasive fibrosarcomas, but metastases were observed in two birds. In two tumor-bearing quail, lymphosarcomas were observed in conjunction with fibrosarcomas. Quail inoculated with m1MSV(B-MuX) virus or quail embryo fibroblast cells infected with helper leukemia virus did not develop tumors. A cell culture derived from one quail tumor was shown to be oncogenic in newly hatched quail. Viruses produced by m1MSV(B-MuX)-infected quail cells or quail tumors had envelope properties of BALB-derived murine xenotropic leukemia virus as measured by host range, interference, and neutralization. Virus structural antigens, proteins with molecular weights of 30,000 and 70,000, were detected in tumors and tumor-derived cell lines by immunofluorescence and gel diffusion. Sera from tumored quail had high titers of type-specific BALB-derived murine xenotropic leukemia virus antibodies as determined by neutralization and immunoprecipitation. Antibodies to the putative m1 Moloney sarcoma virus mos gene product were not detected in sera from tumored or regressor quail.

Animals↗

Experimental toxoplasmosis in bobwhite quail (Colinus virginianus).

Twenty-four 3-5-mo-old battery-hatched bobwhite quail were inoculated orally with 10(5) (ME 49 strain, group A, 6 birds), 10(4) (ME 49 strain, group B, 6 birds), 10(5) (GT-1 strain, group C, 6 birds), and 10(4) (GT-1 strain, group D, 6 birds) Toxoplasma gondii oocysts. One quail in group B died 18 days after inoculation (DAI) due to undetermined etiology. Two quail from group C and 1 quail from group D given GT-1 oocysts died of acute toxoplasmosis 6, 7, and 8 DAI, respectively; numerous T. gondii tachyzoites were found in lesions in visceral tissues. The surviving quail in group A and B were killed 106 DAI and those in groups C and D were killed 60 DAI. Toxoplasma gondii was isolated from pooled tissues of 4 of 5 quail in group B. Brains, hearts, and skeletal muscles from quail in groups A, C, and D were bioassayed individually in mice; T. gondii was isolated from the brains of all 6, hearts of 3, and skeletal muscles of 2 of the 6 quail in group A; from the brains of all 4, hearts of 1, and skeletal muscles of 2 of the 4 quail in group C; and from the brains of all 5, hearts of 1, and skeletal muscles of 3 of the 5 quail in group D. Toxoplasma gondii antibodies were found in sera of all 20 quail killed 60 or 106 DAI. Antibody titers detected in the modified agglutination test using whole tachyzoites were higher than in latex agglutination and indirect hemagglutination tests that used soluble antigens. Antibodies were not detected in a 1:4 dilution of 19 of 20 quail sera in the Sabin-Feldman dye test.

Agglutination Tests↗

Abnormality in the optic nerve of albino mutant quails.

Comparative studies were made between the optic nerves of albino and normal quails. The ipsilateral and contralateral retinofugal projections in the albino quail were similar to those in the normal quail. The abnormality of uncrossed projections in the visual pathways, which is found in albinos of many different mammalian species, was not present in the albino quail. The total cross-sectional area of the optic nerve was approximately 25% smaller in the albino quail than in the normal quail, whereas the fiber density was about 17% higher in the former. The total number of optic nerve fibers in normal and albino quails was therefore the same. Numerous unmyelinated fibers existed in normal and albino quail optic nerves, the ratio of myelinated to unmyelinated fibers being approximately 4:6. Axon diameters of myelinated and unmyelinated fibers in the optic nerves were smaller for the albino quail than for the normal quail. The number of the myelin rings in the albino quail slightly decreased compared with those in the normal quail.

Albinism, Oculocutaneous↗

Composition and muscle cellularity of Japanese Quail after selection for high body weight under an optimal or suboptimal nutritional environment.

The purpose of this study was to determine if the compositional and cellularity changes associated with selection for rapid growth rate in an optimal and suboptimal nutritional environment were similar. The P-line Japanese quail had undergone long-term selection for high 4-week body weight and received a 28% protein diet. The unselected C-line quail received the same diet. T-line quail were selected by the same criteria as P-line quail but received a 20% protein diet containing .2% thiouracil. Body weights and muscle weights of P- and T-line quail were similar at 10 days of age. At 56 days T-line body weight and muscle weights were intermediate between C- and P-line quail, but whole body composition of P- and T-line quail was similar. The P- and T-line quail possessed a greater apparent number of muscle fibers than C line quail. Total muscle DNA content was lower in T-line muscles compared to P-line muscles at 56 days of age. No differences within age were observed among lines of myofiber diameter, fiber type composition, for concentrations of DNA, RNA and protein, or for protein/DNA and RNA/DNA. At 10 days the weight, length and diameter of the humerus and femur bones were greatest in T-line quail; these same parameters were intermediate between C- and P-line quail at 28 and 56 days of age. It was concluded that selection for rapid growth rate per se caused apparent fiber number and fiber length to increase while the effect of suboptimal nutritional environment was not evident until after 10 days of age. Selection under suboptimal conditions as exercised in this study prevented expression of the maximum number of muscle DNA units.

Animals↗

Successful xenogeneic transplantation in embryos: induction of tolerance by extrathymic chick tissue grafted into quail.

In previous experiments, we have demonstrated that limb buds engrafted during embryonic life at E4, between MHC-mismatched chick embryos, are not only tolerated after birth, but induce in the recipient a state of split tolerance toward cells expressing the donor MHC haplotype: donor's skin grafts are permanently tolerated while a proliferative response of host's T cells is generated in MLR by donor-type blood cells. If the same experiment is performed, using quail embryo as a donor and chick as a recipient, acute rejection of the quail limb starts during the first two weeks after birth, thus suggesting that the peripheral type of tolerance induced in these experiments can be obtained only in allogeneic but not in xenogeneic combinations. We report here the unexpected result that when a chick limb bud is grafted into a quail at E4, it is tolerated and, like allogeneic grafts in chickens, induces adult skin-graft tolerance without modifying the MLR response. Similar results were obtained with grafts from another closely related species of bird, the guinea fowl from the Phasianidae family. In contrast, xenogeneic combinations involving more distant species (chick and quail as recipients and duck, an Anatidae, as donor) resulted in strong and early rejection from both recipients. As a whole, quails exhibit a greater ability than the chick to become tolerant to antigens presented peripherally from early developmental stages. In adult quails, however, skin grafts performed in either direction (i.e., quail to chick or the reverse) are rejected according to a similar temporal pattern. Moreover, lymphocytes of both species are able to respond equally well to quail or chick IL-2. Several hypotheses are envisaged to account for these observations. It seems likely that this type of tolerance is directly related to antigenic load because the load in chick to quail wing chimeras is larger than that in quail to chick chimeras. This view is supported by the protracted delay in graft rejection observed when two quail wing buds instead of one are grafted into chickens.

Animals↗

Studies on avian spinal cord chimeras. II. Immune response of the chicken host to the graft of quail tissue.

A previous study described clinical and pathological manifestations observed in 49 chimeras produced by replacing a small fragment of the neural tube of a chicken embryo by a similar fragment from a Japanese quail embryo. Predominant antibodies in sera of these birds were directed against xenogeneic antigens which are devoid of organ specificity and which are present in quail tissues but absent from chicken tissues. Mixed agglutination test with quail cell monolayers detected such antibodies in sera of all chimeras tested. In most instances, positive reactions were observed already in the 4th week after hatching; they persisted in all birds throughout the observation period of up to 8 months. Some of the detected antibodies were directed against saline-nonextractable surface antigens of quail cells. Enzyme immunoassay with quail organ extracts, agglutination of quail tissue particles, and indirect immunofluorescence test with quail organ sections were positive with sera of many, but not all, chimeras. CNS-specific antibodies, apparently autoantibodies, were detected in serum samples of only one chimera, using enzyme immunoassay with extract of chicken brain and indirect immunofluorescence test with sections of chicken spinal cord. Eluates from lesional spinal cord contained antibodies to non-organ-specific quail antigens but not to CNS-specific antigens. Cerebrospinal fluids of many chimeras had antibodies to quail antigens, but no evidence for antibody formation within the CNS was obtained. Cell-mediated immunity could be demonstrated in all chimeras tested by means of lymphocyte proliferation test after stimulation by quail organ extract. It was concluded that pathological events in the studied chimeras have been most likely mediated primarily by humoral immune responses to non-organ-specific quail antigens.

Animals↗

Neurotoxic effects of 2,5-hexanedione on normal and neurofilament-deficient quail.

The neurotoxic effects of 2,5-hexanedione (2,5-HD) were investigated using neurofilament (NF)-deficient (Quv) Japanese quail in comparison with normal Japanese quail. Both Quv and normal Japanese quail were inoculated intraperitoneally with 350 mg/kg/day 2,5-HD for 6 consecutive wk. The results of 2,5-HD exposure differed substantially between the 2 strains of Japanese quail. The 2,5-HD-exposed normal quail showed leg paralysis about 4 wk after initiation of dosing. Some treated normal quail fell into dysstasia and died of nutritional disturbances. Histologically, 2,5-HD-treated normal quail had NF-rich axonal swellings and degeneration in the distal parts of the peripheral nerves, spinal cord, and cerebellar peduncles. In contrast, 2,5-HD-injected Quv quail showed tonic convulsion, ataxia gait, severe quivering, and excitation about 2-3 days after administration. Some treated Quv birds died immediately after systemic tonic convulsion, probably because of asphyxia. Although all treated Quv quail showed neurologic signs, there were no recognizable 2,5-HD-induced lesions in the nervous system. After about 4-6 wk of dosing, 2,5-HD induced distal axonopathy in normal quail and acute neurotoxicity in Quv quail.

Animals↗

Effect of dietary cholesterol on the activities of key enzymes of cholesterol metabolism in hyperlipidemia- and atherosclerosis-prone Japanese quail.

The hyperlipidemia- and atherosclerosis-prone (HAP) Japanese quail is a strain developed for the study of atherosclerosis by genetic selection from the commercially available (CA) Japanese quail. To delineate the characteristics of cholesterol metabolism in this strain, concentrations of serum lipids as well as hepatic enzyme activities were compared between HAP and CA quail. The hepatic enzymes studied are involved in the key step reaction in cholesterol metabolism: HMG-CoA reductase, ACAT, and cholesterol 7 alpha-hydroxylase. The animals were fed ad libitum with either 1% cholesterol or cholesterol-free semipurified diet for 28 days. Although a significant increase (p < 0.01) in serum cholesterol was observed in both strains on elapse of cholesterol feeding, formation of atheroma was seen exclusively in HAP quail of the cholesterol-fed group. The serum and liver cholesterol levels of HAP quail fed the cholesterol diet were significantly higher (p < 0.01) than those of CA quail. No significant differences were seen in the rate of cholesterol biosynthesis (HMG-CoA reductase activity), cholesterol ester formation (ACAT activity) and cholesterol catabolism (7 alpha-hydroxylase activity) between CA and HAP quail. Furthermore, the fecal excretions of acidic and neutral sterol showed no significant difference between strains. Although the formation of atheroma in HAP quail may be presumably due to the contribution of the marked increase in serum cholesterol level, the rate of cholesterol catabolism and synthesis in HAP quail compared well with those of CA quail. These observations suggest that the retarded rate of cholesterol biosynthesis or catabolism is not responsible for hypercholesterolemia in HAP quail.

Animals↗

The influence of dietary protein level on body weight of Japanese quail lines selected under high- and low-protein diets.

Two experiments were conducted to determine the protein requirement of quail lines (P and T) following selection for increased 4-wk BW under normal-protein (28% CP) and low-protein (20% CP) diets, respectively. Quail progeny from Generation 39 breeders were fed diets containing 18, 21, 24, and 27% CP from 0 to 5 wk of age in Experiment 1, whereas in Experiment 2, quail progeny from Generation 79 breeders were fed diets containing 18, 21, 24, 27, and 30% CP from 0 to 4 wk of age. Quail from the unselected base population (C line) were also included in both experiments. Significant line, diet, and line by diet interactions were present in both experiments. At 2 wk of age, T line quail were significantly (P < .05) larger than P line quail across diets, whereas by 4 wk, BW of P line quail were significantly larger than those of T line quail. Across dietary protein levels, quail receiving diets containing 24% CP or higher were significantly larger than those receiving the 18 and 21% CP diets. Quail in both the P and C lines had larger BW with increasing protein levels and an apparent protein requirement between 24 and 27% CP. However, quail in the T line showed no BW response to increased protein levels, indicating that long-term selection for increased BW on a 20% CP diet had altered the protein requirement in this line.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Effects of 2 G hypergravity exposure on Bobwhite (Colinus virginianus) and Japanese quail (Coturnix coturnix japonica).

We compared reproductive fitness and early postnatal growth of Bobwhite (Colinus virginianus) and Japanese (Coturnix coturnix japonica) quail incubated and hatched during 2 G centrifugation. Fertilized Bobwhite and Japanese quail eggs were placed in portable incubators on the 8-ft International Space Station Test Bed (ISSTB) Centrifuge at NASA Ames Research Center. The quail eggs were incubated throughout hatching and reared until Postnatal day (P)4 at either 1.0, 1.2 or 2.0 G. Two days before hatching, candling revealed significantly greater numbers of viable Bobwhite than Japanese quail eggs at all g-loads. Bobwhite quail exhibited significantly better hatching success at all g-loads than did Japanese quail. Bobwhite hatchlings were sensitive to gravitational loading as evidenced by reduced postnatal body mass and length of 2 G hatchlings relative to 1 G control hatchlings. In contrast, mass and length of Japanese quail hatchlings were unaffected by 1.2 or 2 G exposure. Together, our findings provide evidence for superior viability and hatching success in Bobwhite quail relative to Japanese quail, coupled with greater sensitivity of postnatal body growth and development to 2 G loading. Bobwhite quail may be better suited than Japanese quail for scientific studies on space biology platforms.

Animals↗

Steroidogenic properties of isolated adrenocortical cells from Japanese quail selected for high serum corticosterone response to immobilization.

The effect of selection for high stress response on adrenocortical function was examined by measuring the corticosterone response of adrenocortical cells isolated from random-bred Japanese quail and quail selected for high serum corticosterone response to immobilization (high-stress). Highly enriched adrenocortical cells were incubated with various concentrations of ACTH1-24 (ACTH), 8-bromo-cyclic AMP (8Br-cAMP) and pregnenolone for 2 hr. Corticosterone production was measured by radioimmunoassay. Basal corticosterone production values by cells from random-bred and high-stress birds were not different. In contrast, the average maximal ACTH- and 8Br-cAMP-induced corticosterone production by cells from high-stress quail was 89% greater than that of cells from random-bred quail. However, the average pregnenolone-supported corticosterone production by cells from high-stress birds was 34% less than that of cells from random-bred birds. Thus, the data suggest that although random-bred quail cells had a greater potential capacity for corticosterone production, high-stress quail cells had a greater ability to couple ACTH, ACTH-transmembrane-signaling factors and subsequent second messengers with the available steroidogenic enzyme pool. The magnitude of the differences in function between cells from high-stress and random-bred birds was greater for female cells compared to male cells. In addition to differences in cellular function, there were also differences in adrenal and relative adrenal weights between random-bred and high-stress quail. The average, adrenal and relative (mg/100 g body weight) adrenal weights of high-stress quail were 14-16% greater than those of random-bred quail. It is concluded that the enhanced serum corticosterone response of the high-stress quail line is, in part, due to an increase in relative adrenal weight and an increase in adrenocortical cell responsiveness to ACTH.

Adrenal Cortex↗

Exposure of California quail to organophosphorus insecticides in apple orchards in the Okanagan Valley, British Columbia.

We studied the exposure and effect of the organophosphate insecticides azinphos-methyl and diazinon on adult California quail (Callipepla californica) in an apple orchard in the Okanagan Valley, British Columbia. Cholinesterase activity was measured in plasma samples (n = 65) collected from 54 individuals either prior to spraying, immediately (< 24 hours) or 10 days after three spray events. Mean plasma cholinesterase levels declined significantly (P < 0.05, n = 12) to 61% of pre-spray mean activity (controls) immediately following the first spray event, but by ten days had recovered to 86% of mean control activity. Subsequent spray events caused no significant declines in mean plasma cholinesterase activity. Four of the 26 quail sampled within 24 h of a spray event exhibited plasma-ChE inhibition exceeding 50% inhibition. Radio-tagged quail (n = 25) were monitored throughout the breeding season to determine use of orchards and detect changes in use patterns resulting from the spraying of insecticides. Use of orchards by quail varied over the summer, with the highest use occurring in May, declining to very low use by July. Quail exhibited a diurnal pattern, roosting in sparsely forested uplands at night, travelling to orchard areas to feed early each morning and returning to roosts at dusk. Orchard use by quail differed during spray events compared to non-spray times. During the three hour period immediately after spraying (0530-0800), 14-20% of observed quail were in the orchard, after which use declined to < 4%, and returned to 12% by the next day. During non-spray times, 3-13% of radio-tagged the quail were observed in orchard habitat, with the heaviest use (13%) occurring later in the day (0830-1700 h). Seven radio-tagged quail were predated during the study period. However, no deaths could be attributed to insecticide poisoning as carcasses were not in suitable condition for testing. It was concluded that adult quail using orchard habitat early in the summer may be acutely poisoned by anti-cholinesterase insecticides, but the risk of exposure declined over the summer.

Agriculture↗

Patterns of Genetic Diversity Within Three California Quail Species Are Best Explained by Climate and Landscape Changes.

Many North American game animals experienced severe population declines during the 19th century due to market hunting. However, estimates of the timing and magnitude of these declines often rely on anecdotal evidence, which makes it difficult to understand the lasting impacts of hunting pressures versus climate or landscape changes on the genetic diversity of contemporary populations. Historical reports suggest the California quail (Callipepla californica) suffered more significant hunting pressure in the late 19th century relative to either Gambel's (Callipepla gambelii) or mountain quail (Oreortyx pictus). Genomic data can help illuminate the extent to which historical exploitation moulded the genetic health of modern quail populations. We compared whole genome sequences from these three quail species to evaluate whether reported differences in hunting pressure affected contemporary patterns of genetic diversity. Contrary to our expectations, California quail did not exhibit any evidence for population declines until the late 20th century, long after the era of market hunting ended. California quail also exhibited the highest levels of genetic diversity across most analyses with evidence for population expansion over the past 500,000&#x2009;years. In contrast, the mountain quail exhibited a long-term population decline beginning in the middle of the last ice age 30-40 thousand years ago. The Gambel's quail appears to have suffered a more recent bottleneck in association with a major drought that impacted the desert southwest during the mid-20th century. Gambel's quail also exhibited increased realised genetic load for mild and moderately deleterious genetic variants. Together, our results demonstrate that market hunting had little lasting impact on the genetic diversity of these quail species, whereas landscape and climate changes have led to fluctuations in effective population size (Ne) and the buildup of genetic load.

Animals↗

The major histocompatibility complex (Mhc) class IIB region has greater genomic structural flexibility and diversity in the quail than the chicken.

BACKGROUND: The quail and chicken major histocompatibility complex (Mhc) genomic regions have a similar overall organization but differ markedly in that the quail has an expanded number of duplicated class I, class IIB, natural killer (NK)-receptor-like, lectin-like and BG genes. Therefore, the elucidation of genetic factors that contribute to the greater Mhc diversity in the quail would help to establish it as a model experimental animal in the investigation of avian Mhc associated diseases. AIMS AND APPROACHES: The main aim here was to characterize the genetic and genomic features of the transcribed major quail MhcIIB (CojaIIB) region that is located between the Tapasin and BRD2 genes, and to compare our findings to the available information for the chicken MhcIIB (BLB). We used four approaches in the study of the quail MhcIIB region, (1) haplotype analyses with polymorphic loci, (2) cloning and sequencing of the RT-PCR CojaIIB products from individuals with different haplotypes, (3) genomic sequencing of the CojaIIB region from the individuals with the different haplotypes, and (4) phylogenetic and duplication analysis to explain the variability of the region between the quail and the chicken. RESULTS: Our results show that the Tapasin-BRD2 segment of the quail Mhc is highly variable in length and in gene transcription intensity and content. Haplotypic sequences were found to vary in length between 4 to 11 kb. Tapasin-BRD2 segments contain one or two major transcribed CojaIIBs that were probably generated by segmental duplications involving c-type lectin-like genes and NK receptor-like genes, gene fusions between two CojaIIBs and transpositions between the major and minor CojaIIB segments. The relative evolutionary speed for generating the MhcIIBs genomic structures from the ancestral BLB2 was estimated to be two times faster in the quail than in the chicken after their separation from a common ancestor. Four types of genomic rearrangement elements (GRE), composed of simple tandem repeats (STR), were identified in the MhcIIB genomic segment located between the Tapasin-BRD2 genes. The GREs have many more STR numbers in the quail than in the chicken that displays strong linkage disequilibrium. CONCLUSION: This study suggests that the Mhc classIIB region has a flexible genomic structure generated by rearrangement elements and rapid SNP accumulation probably as a consequence of the quail adapting to environmental conditions and pathogens during its migratory history after its divergence from the chicken.

Animals↗

Implants of quail thymic epithelium generate permanent tolerance in embryonically constructed quail/chick chimeras.

In situ implantation of a quail wing bud into a chick embryo at 4 days of incubation (E4) regularly results in the normal development of the implant followed by its acute rejection starting within two weeks post-hatching. If the epithelial thymic rudiments of the quail donor are implanted into the branchial arch area of the chick recipient after partial removal of its own thymic primordia, a chimeric thymus develops in the chick host and this induces tolerance to the quail wing by the chick recipient. The species identity of cells in chimeric thymuses was mapped using Feulgen-Rossenbeck' staining and immunolabelling with monoclonal antibodies directed against quail or chick B-L antigens. Certain lobes contained only chick cells both at the stromal and hemopoietic cell levels. Others had a quail epithelial stroma containing host hemopoietically derived cells. Only chimeras in which at least one third of the thymic lobes were chimeric showed permanent tolerance to the grafted wing. Since the two species exhibit distinct developmental rates, we decided to study the kinetics of thymic involution after birth. Although the changes in thymus weight and histological structure are fundamentally similar in quail and chick, those in the quail start about 7-8 weeks earlier. In the chimeric thymuses, the lobes whose epithelial cells were quail involuted at the rate of control quail showing no influence of the hemopoietic thymic compartment in this process. Tolerance induced by the thymic epithelium during embryogenesis and in early postnatal life was maintained after a profound involution of the quail thymic graft had occurred.

Animals↗

Does the subepicardial mesenchyme contribute myocardioblasts to the myocardium of the chick embryo heart? A quail-chick chimera study tracing the fate of the epicardial primordium.

Morris (J. Anat., 1976;121:47-64) proposed that the subepicardial mesenchyme might represent a continuing source of myocardioblasts during embryonic and fetal development. Recent studies have shown that the epicardium and subepicardial mesenchyme, and the coronary vasculature are all derived from a region of the pericardial wall, called the proepicardial serosa. In avian embryos, the cells from the proepicardial serosa colonize the heart via a secondary tissue bridge formed by attachment of proepicardial villi to the heart. In the present study, Morris's hypothesis was tested by tracing the fate of the proepicardial serosa. This was achieved by constructing quail-chick chimeras. The proepicardial serosa was transplanted from HH16/17 quail embryos to HH16/17 chick embryos (ED3). A new transplantation technique facilitated an orthotopic attachment of the quail proepicardial villi to the chicken heart, and prevented the attachment of the chicken proepicardial villi to the heart. The fate of the grafted quail cells was traced in chimeras from ED4 to ED18 with immunohistochemistry, using quail-specific antibodies (QCPN, QH-1). From ED4 onward, the transplant was connected to the dorsal heart wall via its proepicardial villi. Starting from the point of attachment of the quail proepicardial villi to the heart, the originally naked myocardium became almost completely covered by quail-derived epicardium, and quail mesenchymal cells populated the subepicardial, myocardial, and subendocardial layers including the av-endocardial cushions. Quail cells formed the endothelial and smooth muscles cells of the coronary vessels, and the perivascular and intramyocardial fibroblasts. Quail myocardial cells were never found in the subepicardial, myocardial, and subendocardial layers. This suggests that the subepicardial mesenchyme normally does not contribute a substantial number of myocardioblasts to the developing avian heart. The new transplantation technique presented facilitates the production of chimeric hearts in which the derivatives of the proepicardial serosa are almost completely of donor origin. This technique might be useful for future studies analyzing the role of certain genes in cardiac development by the creation of somatic transgenics.

Animals↗

Effects of enclosure size on sexual behavior of Japanese quail (Coturnix japonica).

The authors determined whether results of experiments on copulatory and affiliative behavior of pairs of Japanese quail (Coturnix japonica) conducted in a closely confining apparatus would predict behavior in a large enclosure in which female quail could avoid contact with male quail. As found previously in studies of closely confined quail, in a large enclosure containing numerous barriers, both unmated female quail and mated female quail laying unfertilized eggs were more likely to remain near a confined male quail than were mated female quail laying fertilized eggs. Furthermore, the number of copulations that a pair engaged in when closely confined predicted the number of copulations that they engaged in when they were in the large enclosure. Patterns of affiliation and of mating in a confining laboratory apparatus thus predicted behavior in a larger enclosure that provided female quail with opportunity to avoid contact with male quail.

Animals↗