Glycogen metabolism in the developing accessory lobes of Lachi in the nerve cord of the chick: metabolic correlations with the avian glycogen body

Glycogen synthase, glycogen phosphorylase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glucose-6-phosphatase were determined for the first time in the necessary lobes of Lachi from late embryonic chicks. The activities of these enzymes were compared with those found in other glycogen-metabolizing tissues, specifically the glycogen body, liver, and skeletal muscle, obtained from the same embryos. The data show that, as in the glycogen body, the accessory lobes of Lachi lack glucose-6-phosphatase, but contain relatively high activity levels of glycogen synthase I, total and active glycogen phosphorylase, and the dehydrogenases of glucose-6-phosphate and 6-phosphogluconate. The percent of glycogen synthase I activity in the Lachi lobes is from two- to 20-fold greater than observed in the glycogen body, liver, or muscle, whereas the percent of glycogen phosphorylase a activity is comparable to that of the liver, but greater than that in the glycogen body or muscle. The activity of each dehydrogenase of the pentose phosphate cycle in the Lachi lobes is similar to that noted in the glycogen body, but is over two- or fivefold greater than that activity found in muscle or liver. Our data, together with other recent evidence, suggest that the role of glycogen in these functionally enigmatic tissues may be to support the precocious process of myelin synthesis in the developing bird, as well as possibly to provide alternate sources of energy for the avian central nervous system.     

Glycogen metabloism in the developing chick glycogen body: functional significance of the direct oxidative pathway.

Glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glucose-6-phosphatase were quantitatively determined for the first time in glycogen body tissue from late embryonic and neonatal chicks. For comparative purposes, the activities of these enzymes were examined also in liver and skeletal muscle from pre- and post-hatched chicks. The present data show that both the embryonic and neonatal glycogen body lack glucose-6-phosphatase, but contain relatively high levels of glucose-6-phosphate dehydrogenase. The activity of each dehydrogenase in either embryonic or neonatal glycogen body tissue is two- to five-fold greater than that found in muscle or liver from pre- or post-hatched chicks. The relatively high activities observed for both dehydrogenases in the glycogen body, together with the absence of glucose-6-phosphatase activity in that tissue, suggest that the direct oxidative pathway (pentose phosphate cycle) of glucose metabolism is a functionally significant route for glycogen utilization in the glycogen body. It is hypothesized that the glycogen body is metabolically linked to lipid synthesis and myelin formation in the central nervous system of the avian embryo.     

Ultrastructural morphology of the genusKineosporia

The ultrastructure ofKineosporia aurantiaca was investigated with phosphotungstic acid negative staining and thin sectioning techniques. Motile spores were observed, each having a polar tuft of flagella. Thick-walled somatic hyphae displayed prokaryotic morphologies. Sporangia were seen having a single spore with no evidence of spore segmentation or branching. The findings were consistent with the light microscopic observations of Pagani and Parenti.     

Ultrastructural localization of glycogen in erythrocytes and developing erythrocytic cells in normal human bone marrow

Summary The periodic acid-thiosemicarbazide-silver proteinate (PA-TSC-SP) reaction was employed for the ultrastructural cytochemical localization of saliva-labile glycogen in the erythrocytic cells in normal human blood and bone marrow. Particulate glycogen was demonstrated in the cytoplasm of all developmental forms of erythrocytic cells from the proerythroblast through the reticulocyte; a few particles of glycogen also were present in mature erythrocytes even in the peripheral blood. Statistical evaluation of the number of glycogen particles in mid-plane cell sections at each morphological stage of development indicated a significant and stepwise decrease during cellular maturation. This change in glycogen content may reflect both cellular utilization and mitosis during the maturational sequence.Supported by Grant No. SR01AM 12084-15 from the National Institutes of Health, Bethesda, Maryland.Appreciation is expressed to Anita Topson, Barbara Speakmon and Marjorie Griffith for their technical assistance and to Dr. Gerald King for performing the bone marrow aspirations.     

Epigenesis in developing avian scales. I. Qualitative and quantitative characterization of finite cell populations

Throughout a period from day 8.5 to day 12.5 of incubation of a chick embryo, a finite cell population of scale epidermis was characterized from various view points such as cellular organization, position, shape, area, number of constituent cells, density, and cell proliferation activity. In this study, the preparation of whole mount specimens was found to be quite valuable. On day 8.5, cells in the prospective scale region could be morphologically distinguished in the tarsometatarsus at a certain distance proximally away from the tarsometatarsal-phalangeal joint. --On day 9.25, about 1,100 cells became highly columnar in shape and densely associated, forming a placode structure. In both distally and proximally adjacent regions of this placode, the cells were semiquadrate in shape and loosely associated, leading to the formation of the interplacode structures. Such contrasting difference in cell organization between placode and interplacode was preserved from day 9.25 to day 11. During this period, both the area and number of constituent cells increased greatly in the placode and only slightly in the interplacode. However, cell proliferation activity was completely suppressed in the placode, and quite active in the interplacode. The activity in cell proliferation proved to be inversely correlated with the density of basal cells. Throughout the present study, it has been demonstrated that the early development of scale epidermis is achieved through a coordinated activity of the two discrete cell populations: the placode and interplacode.     

Ultrastructural and biochemical evidence of glycogen in the developing lung of the chick embryo: possible contribution to surfactant

1. Glycogen was identified ultrastructurally in undifferentiated type-II cells of the lung of the day 16 chick embryo. 2. By 4 days after hatching, glycogen in type-II cells could not be observed, although lungs were actively secreting surfactant. 3. Biochemical measurements of pulmonary glycogen revealed a depletion during days 14-20 of incubation, corroborating ultrastructural data. 4. Using lung slices, 14C-glucose was incorporated in vitro into pulmonary surfactant phospholipids at a high rate in day 14 embryos, and a significantly lower rate on day 19. 5. Hypophysectomy resulted in sub-normal initial accumulation of pulmonary glycogen on day 14 of development, but did not alter the depletion pattern after day 16. 6. Thus, glycogen stores may contribute to avian embryonic pulmonary surfactant, and accumulation of early stores may be under hormonal control.     

Development of the glycogen body of the Japanese quail, Coturnix japonica. I. Light microscopy of early development

The glycogen body is a functionally enigmatic structure located in lumbosacral region of the spinal cord in birds. This tissue is unique to birds, and, although it is believed to be present in all species, studies on the glycogen body to date have been confined largely to the domestic chicken. The present study is the first to describe the glycogen body of the Japanese quail (Coturnix japonica) during incubation and at hatching. Light microscopy and histochemistry were used to identify the glycogen body in the spinal cord of the developing quail beginning at 7 days of incubation and to ascertain the presence of nerve fibers in that tissue at hatching.     

The effect of urbanisation on avian morphology and latitudinal gradients in body size

Urban areas occupy a large and growing proportion of the earth. Such sites exhibit distinctive characteristics relative to adjacent rural habitats, and many species have colonised and now successfully exploit urban habitats. The change in selection pressures as a result of urbanisation has led to trait divergence in some urban populations relative to their rural counterparts, but studies have generally been local in scale and the generality of differentiation thus remains unknown. The European blackbird Turdus merula is one of the commonest urban bird species in the Western Palearctic, but populations vary substantially in the length of time they have been urbanised. Here we investigate patterns of morphological variation in European blackbirds occupying 11 paired urban and rural habitats across much of the urbanised range of this species and spanning 25° of latitude. First, we assessed the extent to which urban and rural blackbirds are differentiated morphologically and the consistency of any differentiation across the range. Paired urban and rural Blackbird populations frequently exhibited significant morphological differences, but the magnitude and direction of differentiation was site dependent. We then investigated whether the nature of latitudinal gradients in body‐size differed between urban and rural populations, as predicted by differences in the climatic regimes of urban and rural areas. Blackbird body‐size exhibited strong latitudinal gradients, but their form did not differ significantly between urban and rural habitats. The latitudinal gradient in body size may be a consequence of Seebohm's rule, that more migratory populations occurring at high latitudes have longer wings. We conclude that while there can be substantial morphological variation between adjacent urban and rural bird populations, such differentiation may not apply across a species’ range. Locality specific differentiation of urban and rural blackbirds may arise if the selection pressures acting on blackbird morphology vary in an inconsistent manner between urban and rural habitats. Alternatively, phenotypic divergence could arise in a stochastic manner depending on the morphological traits of colonists, through founder effects.     

Ultrastructural localization of glycogen in the granulocytes of normal rabbit bone marrow.

The glycogen of rabbit granulocytes has been studied in glutaraldehyde and osmium tetroxide fixed bone marrow by the periodic acid-thiocarbohydrazide-silver proteinate procedure (PA-TCH-SP). The PA-TCH-SP procedure involved the staining of intracytoplasmic glycogen more densely than the routine lead citrate staining. The PA-TCH-SP procedure demonstrated the intracytoplasmic glycogen in all three kinds of granulocytes. Though a sequence of intensity was observed in each stage of cell maturation, intracytoplasmic glycogen increased generally in accordance with cell maturation in the granulocytes. Functional significance of the glycogen in the granulocytes was discussed in relation to its staining. A very weak reaction in the granules of the granulocytes was described in relation to their contents.     

Muscarinic cholinergic binding sites in the developing avian heart.

The potent muscarinic cholinergic antagonist 3-quinuclidinyl benzylate (QNB) has been used to detect and quantify muscarinic receptors in the developing chick heart. Specific binding in microsomal pellets prepared from hearts ranging in age from 70 hr in ovo to adulthood was examined and was found to increase from 4 × 10^?13 moles of [³H]QNB bound/mg of protein at the earliest stage tested to 5 × 10^?12 moles of [³H]QNB/mg of protein at birth and then to drop slightly to 2 × 10^?12 moles of [³H]QNB/mg of protein at the latest age tested. The developmental significance of these results is discussed.