Mutant Quail Research Articles

Day and night dysfunction in intraretinal melatonin and related indoleamines metabolism, correlated with the development of glaucoma-like disorder in an avian model.

As previous studies have suggested that melatonin and serotonin may be involved in the regulation of intraocular pressure, retinal concentrations of melatonin, 5-HT, and related indoleamines measured at day and at night were studied during the development of a glaucoma-like disorder with increased intraocular pressure in the al mutant quail. Indoleamine levels were determined by HPLC with electrochemical detection in 1-month-, 3-month-, and 7-month-old al mutant and control quails. Morphology and numbers of melatonin-synthesizing and 5-HT-containing cells, labelled immunohistochemically with an anti-hydroxyindol-0-methyltransferase (HIOMT) antibody and an anti-5-HT antibody, respectively, were studied. Major findings were that: (1) no significant changes in morphology of melatonin-synthesizing cells or in the morphology and density of 5-HT-containing amacrine cells were observed during the development of glaucoma: (2) 5-HT metabolism was modified during the night at 1 month of age and during the day after 3 months; and (3) melatonin metabolism was modified during the night at 7 months and during the day after 3 months. These results demonstrate a relationship between the temporal evolution of this avian glaucoma and a dysfunction in indoleamine retinal metabolism.

Early embryonic interaction of retinal pigment epithelium and mesenchymal tissue induces conversion of pigment epithelium to neural retinal fate in the silver mutation of the Japanese quail.

The neural retina and retinal pigment epithelium (RPE) diverge from the optic vesicle during early embryonic development. They originate from different portions of the optic vesicle, the more distal part developing as the neural retina and the proximal part as RPE. As the distal part appears to make contact with the epidermis and the proximal part faces mesenchymal tissues, these two portions would encounter different environmental signals. In the present study, an attempt has been made to investigate the significance of interactions between the RPE and mesenchymal tissues that derive from neural crest cells, using a unique quail mutant silver (B/B) as the experimental model. The silver mutation is considered to affect neural crest-derived tissues, including the epidermal melanocytes. The homozygotes of the silver mutation have abnormal eyes, with double neural retinal layers, as a result of aberrant differentiation of RPE to form a new neural retina. Retinal pigment epithelium was removed from early embryonic eyes (before the process began) and cultured to see whether it expressed any phenotype characteristic of neural retinal cells. When RPE of the B/B mutant was cultured with surrounding mesenchymal tissue, neural retinal cells were differentiated that expressed markers of amacrine, cone or rod cells. When isolated RPE of the B/B mutant was cultured alone, it acquired pigmentation and did not show any property characteristic of neural retinal cells. The RPE of wild type quail always differentiated to pigment epithelial cells. In the presence of either acidic fibroblast growth factor (aFGF) or basic FGF (bFGF), the RPE of the B/B mutant differentiated to neural retinal cells in the absence of mesenchymal tissue, but the RPE of wild type embryos only did so in the presence of 10-40 times as much aFGF or bFGF These observations indicate that genes responsible for the B/B mutation are expressed in the RPE as well as in those cells that have a role in the differentiation of neural crest cells. They further suggest that development of the neural retina and RPE is regulated by some soluble factor(s) that is derived from or localized in the surrounding embryonic mesenchyme and other ocular tissues, and that FGF may be among possible candidates.

Changes in aminergic retinal systems during the development of glaucoma in a mutant of quail

Changes in aminergic retinal systems during the development of glaucoma in a mutant of quail

A new inherited muscular disorder in Japanese quails (Coturnix coturnix japonica).

Thirteen adult mutant (LWC strain) Japanese quails (Coturnix coturnix japonica), between the ages of 8 and 60 weeks were examined for a progressive muscular disorder. The disorder, inherited as an autosomal dominant trait, was clinically apparent as early as 28 days of age; it was characterized by generalized myotonia, muscle stiffness, and muscle weakness. Affected birds were identified by their inability to lift their wings vertically upward and by their inability to right themselves when placed on their dorsum. Electromyographic studies in two mutant quails showed high-frequency repetitive discharges comparable to those of myotonic runs. These discharges persisted after nerve resection. The distinctive histopathologic changes in the various muscles examined were ring fibers, sarcoplasmic masses, and internal migration of sarcolemmal nuclei. A slight decrease in the size of type IIB muscle fibers and a slight increase in the size of type IIA fibers were observed in the M. pectoralis thoracicus of affected quails. In older affected birds, inter- and intrafascicular fatty infiltration with replacement of type IIB fibers by fat cells was seen in the pectoral muscles. Single fiber necrosis, nonspecific lymphorrages, and variations in the muscle fiber size and shape were also noted. The typical muscle lesions and multisystem involvement, which was manifested by testicular degeneration and atrophy in the male LWC specimens and bilateral lenticular cataracts in 6 of 13 affected mutant quails, suggest resemblance of this new inherited muscular disorder to myotonic dystrophy in man.

Smaller axon and unaltered numbers of microtubules per axon in relation to number of myelin lamellae of myelinated fibers in the mutant quail deficient in neurofilaments.

To characterize the morphological features of the myelinated fibers in the mutant quails deficient in neurofilaments (NF), caused by a nonsense mutation in the NF-L gene, the morphological parameters of the axon and myelin sheath, and their relationships in the peroneal nerve were evaluated. In the mutant, the axonal area was smaller than in the control (P > 0.01), reflecting the lack of large diameter axons. There was no significant difference in the mean number of myelin lamellae and of their spacings between controls and mutants. Therefore, it was decided to analyze the alteration of axonal parameters in relation to the number of myelin lamellae. In the regression analysis, the number of microtubules (MT) per square micrometer of the axonal area was greater in the mutant than in the control (P < 0.05); however, the number of MT per axon was similar in controls and mutants with the same given number of myelin lamellae. The number of MT+NF per axon was smaller in the mutant than in the control only for myelinated fibers with more than 25 myelin lamellae (P > 0.05). These findings indicate that there was a less significant effect of NF deficiency on the smaller than on the larger myelinated fibers. There was no compensatory increase in the numbers of MT per axon of the myelinated fibers in the mutant as found previously in the unmyelinated fibers of the mutant.

Smaller axon and unaltered numbers of microtubules per axon in relation to number of myelin lamellae of myelinated fibers in the mutant quail deficient in neurofilaments

Smaller axon and unaltered numbers of microtubules per axon in relation to number of myelin lamellae of myelinated fibers in the mutant quail deficient in neurofilaments

The villin-like protein encoded by the Drosophila quail gene is required for actin bundle assembly during oogenesis

Mutations in the Drosophila quail gene result in female sterility due to the disruption of cytoplasmic transport from the nurse cells into the oocyte late in oogenesis. Nurse cells from quail mutant egg chambers fail to assemble cytoplasmic actin filament bundles correctly. We have cloned the quail gene and found that it encodes a protein with homology to the vertebrate actin-regulating protein villin. Unlike vertebrate villin, which is restricted to specialized absorptive epithelial cells, the villin-like protein encoded by quail is germline specific in adult files. Antibodies directed against the quail protein show a striking colocalization with filamentous actin in the nurse cells and the oocyte. Our results demonstrate that the villin-like product of quail is required for the formation of cytoplasmic actin filament bundles in nurse cells, possibly by regulating both the polymerization and organization of actin filaments as demonstrated for vertebrate villin in vitro.

Greater number of microtubules per axon of unmyelinated fibers of mutant quails deficient in neurofilaments: possible compensation for the absence of neurofilaments.

Morphometric evaluations were performed on the peroneal nerve from mutant quails deficient in neurofilaments (NF) to elucidate the effect of an absence of NF on unmyelinated axons. The diameter frequency distribution of unmyelinated axons was similar between controls and mutants. The mean transverse axonal area, axonal circumference and circularity index of the unmyelinated axons were also similar in controls and mutants. However, the number of microtubules (MT) per axon was greater (P < 0.01) in the mutants than in the controls. The regression analysis relating the number of MT per axon to the diameter of unmyelinated axons indicated a greater number of MT in the mutants than in the controls (P < 0.05-0.01). A significantly greater number of MT per axon in the mutants may suggest a compensatory increase of MT in the absence of NF. This may conserve the size and transverse circular profile of the unmyelinated axons which are probably maintained by both MT and NF in the controls. The number of MT may be increased at the expense of the soluble fraction of tubulin.

Greater number of microtubules per axon of unmyelinated fibers of mutant quails deficient in neurofilaments: possible compensation for the absence of neurofilaments

Greater number of microtubules per axon of unmyelinated fibers of mutant quails deficient in neurofilaments: possible compensation for the absence of neurofilaments

Identification of ommin in the integument of the silkworm, Bombyx mori.

An ommin was isolated from the integument of the quail mutant of the silkworm, Bombyx mori, using column chromatography on SP-Sephadex and cellulose powder. As a standard, ommin was isolated from diapause eggs of the normal silkworm. The red pigment from the larval integument of quail mutants was identical to the standard compound with respect to absorption spectrum, infrared spectrum and RF values in thin-layer chromatography (TLC). After acid hydrolysis of the pigment, 3-hydroxykynurenine was detected by TLC. This is the first report of an ommin in a lepidopteran larval integument.

Smaller number of large myelinated fibers and focal myelin thickening in mutant quails deficient in neurofilaments.

The peripheral nervous system of a mutant of a Japanese quail deficient in neurofilaments (mutant) and of a normal Japanese quail (control) was morphometrically evaluated to characterize the morphological findings, especially those of the myelinated fibers of the mutant. In the proximal peroneal nerves, the frequency of the teased myelinated fibers showing the focal myelin thickening was higher in mutant than in control (P < 0.001) without obvious ongoing axonal degeneration and segmental demyelination. The total numbers of the myelinated fibers in the proximal and distal peroneal nerve, and in the tibial nerve branch to gastrocnemius muscle (pars medialis) were similar between control and mutant, although the number of the large myelinated fibers was less (P < 0.01) and the number of the small myelinated fibers was greater (P < 0.01) in mutant compared with control. The median diameters of neuronal cell bodies of the sacral dorsal root ganglia were similar in control and mutant. The percentages of light, dark and unclassified cells evaluated based on the histologic cytoplasmic features were also similar in control and mutant. Therefore, morphometric alterations were more pronounced in the peripheral myelinated nerve fibers compared with those in the cell bodies of the spinal dorsal root ganglia. We concluded that a smaller number of large myelinated fibers with a greater number of small myelinated fibers and the presence of focal myelin thickening are the main morphologic findings in this mutant, probably due to the arrest of radial growth or maturation of the axons of the myelinated fibers in the absence of ongoing myelinated fiber degeneration.

Reduced diameter and conduction velocity of myelinated fibers in the sciatic nerve of a neurofilament-deficient mutant quail

The diameter and conduction velocity of myelinated fibers in the sciatic nerve isolated from neurofilament-deficient quail (‘quiver’) were compared with those from wild quail. The diameter was significantly reduced in quiver, however, the frequency distribution formed three peaks as did that observed in the wild. The fibers were categorized in three groups possessing different conduction velocity. The conduction velocity appeared to be proportional to the diameter in each strain, and was significantly reduced in quiver. These results indicate that, although the diameter and conduction velocity are reduced in quiver fiber, the correlation between the parameters observed in wild quail is still preserved.

Dopaminergic Interplexif orm Cells in the Retina of Pigmented and Hypopigmented Quails (Coturnix coturnix japonica)

Interplexiform cells (IPCs) have not been previously described as a component of the population of tyrosine hydroxylase (TH) immunoreactive (presumably dopaminergic) cells in the avian retina. In this study, carried out in both pigmented and imperfect albino mutant quails (Coturnix coturnix japonica), we initially describe TH immunoreactive cells in the inner nuclear layer whose internal dendritic arborization extends into strata 1, 3 and 4/5 of the inner plexiform layer. Then, we describe ascending processes arising from the somata or proximal dendrites of these cells. These sclerally directed processes (100-1,000 microns long) run across the inner nuclear layer to terminate within the outer plexiform layer, sometimes even reaching the outer nuclear layer. Hence, the cells bearing such processes correspond well with the definition of IPCs. The number of scleral processes is higher in mutant (48 +/- 19/retina) than in normal (12 +/- 10/retina) quails and are distributed throughout the retina except the area surrounding the pecten. Comparison of biochemical assays for dopamine in the two strains reveals a significantly higher dopamine content in the mutant quails which could be related to its increased number of dopaminergic IPC processes.

Japanese quail and human acid maltase deficiency: A comparative study

A morphological study was carried out on the skeletal muscle of a mutant Japanese quail with acid maltase deficiency (AMD). The affected quails began to experience difficulty in lifting their wings about 6 weeks after hatching. Four weeks after hatching, before symptoms appeared, alpha-1, 4-glucosidase activity in skeletal muscle was decreased to less than 10% of the control level, and muscle fibers possessed many vacuoles containing periodic acid Schiff (PAS) positive material which was digested by diastase, and showed high acid phosphatase activity. Although both red and white muscles were involved, the pectoralis superficialis (PS, white) muscle was preferentially affected, showing intracytoplasmic vacuoles, variation in fiber size and fatty tissue replacement relatively early in the disease. The quails' disease closely resembled human late onset AMD in the slow clinical course, the presence of residual acid alpha-glucosidase activity and the muscle pathology. This mutant quail seems a useful model for elucidation of the muscle degeneration in human AMD (glycogen storage disease type 2).

Sciatic nerve in mutant quail with neurofilament deficiency: Diameter and conduction velocity of myelinated fibers

Sciatic nerve in mutant quail with neurofilament deficiency: Diameter and conduction velocity of myelinated fibers

External and Internal Abnormalities Exhibited by the Crossbreds between the Ear-Tuft(hfd)and Throat-Tuft(hfdTt)Mutants of Japanese Quail(Coturnix coturnix japonica).

Some of crossbreds between ear-tuft (ET, hfd/hfd) and throat-tuft (TT, hfdTt/hfdTt) mutant quail showed assorted anomalies involving tufts, ear-opening abnormalities, extra bones projecting from the throat, and head-skeleton abnormalities as their parental quail. They were mostly classifiable as ET-or TT-type abnormality, indicating possible correspondence between phenotypes and genotypes. Incidences of 15-day embryos with external abnormalities ranged between 27%-51%, being significantly lower than those of 5-day embryos with hyomandibular furrow (HF) defects (58%-64%). The differences in incidences of abnormal embryos at the two developmental stages suggested the existence of repair mechanisms for the HF defect. Incidences of 15-day embryos having head-skeleton abnormalities ranged between 59%-77%, being significantly higher than those of tufts, ear-opening abnormalities and/or extra bones. These results show that collective investigations on many kinds of characters may be necessary to find out a key character showing accurate correspondence to a genotype when gene effect is expressed in different organs and tissues. Incidences of the head-skeleton abnormalities in the crossbreds mentioned above (59-77%) were significantly lower than those observed in both intra-ET-(87%) and intra-TT-strain crosses (88%), which suggested that interaction among hfd and hfdTt genes and background genes lowers the incidence of the head-skeleton abnormalities. The head-skeleton abnormality was found to be an inadequate character for an allelism test.

Occurrence of xanthommatin containing pigment granules in the epidermal cells of the silkworm, Bombyx mori

A new type of pigment granule was found in the epidermal cells of the quail mutant of the silkworm, Bombyx mori. Electron microscopic observation shows this granule to be dense and distinct from the translucent pteridine granule. After the granules were isolated by sucrose density gradient centrifugation, the pigment was extracted and identified as xanthommatin. Xanthommatin localizes in the pigment granules binding with a protein. By SDS-polyacrylamide gel electrophoresis, the molecular weight of the pigment protein was estimated to be 13 kDa. The pigment granules may have a role in the biosynthesis and accumulation of xanthommatin.

Time course of degeneration of the visual system induced by spontaneous glaucoma in the albino quail ( Coturnix coturnix japonica)

The retinal projection of an imperfect albino quail mutant with a sex-linked recessive gene was examined 2 weeks-16 months post-hatch using various histological methods. During the first weeks the visual system was normal. Initial signs of buphthalmos, a form of spontaneous glaucoma, appeared between the 3th and 5th months. Its devepment induced a degeneration of the retinal projections according to a relatively precise sequence progressing from the mesencephalic tegmentum to the optic tectum, then from the pretectum to the thalamus. The data suggest that the degeneration of the optic axons results from their mechanical compression due to the increased intraocular pressure.

Histopathological changes of the retina and optic nerve in the albino mutant quail ( Coturnix coturnix japonica)

Histopathological changes in the retina and optic nerve in imperfect albino mutant quails with a sex-linked recessive gene were studied ontogenetically. The mutant quail showed eye enlargement 3 months after hatching. The eyes exhibited hazy corneas, lens opacities and deep anterior chambers at 18 months of age. Some ganglion cells in the retina and axons in the optic disc began to degenerate 6 months after hatching. There were many deformed or fragmented ganglion cells at 12 months of age, and axonal degeneration was observed in the optic disc. The optic disc and the retina around it became excavated. At this time, hydropic degeneration was found in the ganglion nerve fibre layer and optic nerve and a small accumulation of acid mucopolysaccharide, which was sensitive to hyaluronidase, was present in the optic disc and optic nerve. The excavation was found to be fully developed around the optic disc at 18 months and most ganglion cells showed degenerative changes. During this period, the inner plexiform and inner nuclear layers showed hydropic degeneration. At 24 months the ganglion cell and ganglion nerve fibre layers had disappeared, the thickness of the inner nuclear layer was reduced and many photoreceptor cells were totally degenerated. The optic nerve was occupied by glial cells, blood vessels and cavernous spaces in which acid mucopolysaccharide accumulated. These histopathological retinal changes in the mutant quail are very similar to those reported in experimentally induced glaucoma of other animal species and to those in human glaucoma. The usefulness of this mutant quail as an animal model for the human disease is discussed.

Decreased synaptic areas on Purkinje spines in the cerebellar cortex of the mutant Japanese quail, Coturnix coturnix japonica

‘Dark frayed feather nervous disorder’ ( dn) is a neurological mutation in quails in which the cerebellar cortex is abnormally organized. Purkinje cells are not aligned in a single row and show hypoplasia of the dendrites. The synapses between the parallel fibers and the spines of the Purkinje cell dendrites were examined with the technique of serial sections in electron microscopy. The postsynaptic thickenings were obviously decreased in the mutant quail despite the same density and size of dendritic spines of Purkinje cells. In addition, ectopic spines and postsynaptic differentiations free of parallel fibers were not found on the dn Purkinje cell. Because of the poor dendritic arborization, the total number of spines and the total synaptic area are, therefore, reduced in the dn Purkinje cell. According to the results obtained the dn mutant genetic locus is considered to affect primarily Purkinje cells.