Biosynthesis of ascorbic acid in chick embryos

Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.     

Lymphocytes, but not cancer cells are able to penetrate into the rat embryo yolk sac wall

Normal rat lymphocytes and cells of 2 highly invasive tumors, the L5222 rat leukemia and the VW rabbit carcinoma, were inoculated in vitro on the mesothelial surface of the visceral wall of the rat embryo yolk sac. After 48 h, lymphocytes, without any damage being inflicted on the mesothelial cells, had penetrated deeply into the yolk sac wall, whereas both kinds of cancer cells had destroyed the mesothelial cells, but not advanced beyond the basal lamina.     

The localization of acetylcholinesterase in the optic lobe in the developing chick embryo

Summary The localization of acetylcholinesterase (AChE) in the optic lobe in the developing chick embryo was studied histochemically and biochemically. The histochemical reaction of AChE increased remarkably between stage 42 and 44 especially in the neuropile. The increase of the biochemical activity of the AChE in the synaptic membrane fraction occurred at a later stage than that in the microsomal fraction. These findings can be interpreted as the result of axonal transport of the enzyme from the synthetic to the synaptic site.Acknowledgments. The authors wish to thank Prof. Yasuharu Kuwahara, Cataract Research Institute, for the use of his cryostat and other laboratory facilities, Dr. Koji Kami, Department of Anatomy, Keio University School of Medicine, for his valuable advice regarding histochemistry.     

Lymphocytes,but not cancer cells are able to penetrate into the rat embryo yolk sac wall

Summary Normal rat lymphocytes and cells of 2 highly invasive tumors, the L5222 rat leukemia and the V2 rabbit carcinoma, were inoculated in vitro on the mesothelial surface of the visceral wall of the rat embryo yolk sac. After 48 h, lymphocytes, without any damage being inflicted on the mesothelial cells, had penetrated deeply into the yolk sac wall, whereas both kinds of cancer cells had destroyed the mesothelial cells, but not advanced beyond the basal lamina.     

Effect of different methods of exposure to cyproterone acetate on mortality in chick embryos

Summary 33-h chick embryos exposed to 0.25 mg or 0.50 mg cyproterone acetate injected into the yolk sac showed a significantly lower mortality rate than embryos receiving the same dosage applied directly onto the developing blastodisc.This work was supported by a Government Research Support Grant awarded to Louisiana State University School of Medicine. Cyproterone acetate supplied through courtesy of Schering AG, Berlin, West Germany.     

Evolutionary implications of ascorbic acid production in the Australian lungfish

Summary It is shown that the Australian lungfish (Neoceratodus forsteri) synthesizes ascorbic acid in its kidney, suggesting that ascorbic acid synthesis started before the origin of the tetrapods.Acknowledgments. We would like to thank Dr G.C. Grigg, University of Sydney, Mr R. B. Humphries, Dr P.A. Janssens and Dr C.H. Tyndale-Biscoe, Australian National University, and Dr. M. Griffiths and J.C. MacIlroy C.S.I.R.O., Division of Wildlife Research for supplying the tissue.     

Receptor-mediated transport and deposition of complement component C3 into developing chicken oocytes

Immunological resistance of the chick embryo is dependent upon IgG present in the yolk of the layed egg. Here we show that complement factor 3 (C3), a key component of the humoral complement system, is a yolk component of chicken eggs. C3 is transported into oocytes by LR8-mediated endocytosis. LR8 also binds and transports other major yolk components such as vitellogenin, very-low-density lipoprotein, and α₂-macroglobulin. Expression studies of LR8 during chicken development and oocyte maturation, in combination with studies on the uptake of individual yolk components, suggest the following model for oocyte maturation in the chicken: all oocytes present in the ovary contain high levels of LR8 mRNA and protein long before the onset of oocyte maturation. Selected oocytes gain access to yolk precursors, and LR8 binds, internalizes, and deposits the major yolk components in the ratio of their relative abundance in the accessible pool.Received 9 May 2005; received after revision 6 June 2005; accepted 13 June 2005     

L-gulonolactone oxidase is present in the invertebrate,Limulus polyphemus

Summary L-Gulonolactone oxidase (EC 1.1.3.8) which catalyzes oxidation of L-gulonolactone to L-ascorbic acid was detected in tissues ofLimulus polyphemus.     

Alteration of cell shape in the early chick embryo mesoderm by neuraminidase

Summary Living chick embryo mesoderm cells (stages 3 to 5) were exposed to neuraminidase. The mesoderm cells changed shape losing their long thin processes and become like primitive streak cells, with short flat processes. Ruthenium red staining of such treated embryos shows that the surface coat on the mesoderm cells is reduced in thickness. These results show that cell shape in the chick embryo mesoderm is at least partly determined by the thickness and the composition of the surface coat.Acknowledgment. It is a pleasure to thank Professor F. Beck for the facilities of the Department of Anatomy, University of Leicester, and Mr. G. L. C. McTurk of the University of Leicester Scanning Electron Microscope Unit for operating the ISI 60 SEM. Mr Jeff Smith and Mrs Doris Duncan gave us valuable technical assistance and Dr. A. J. Rowe kindly allowed us to use the facilities of the Electron Microscope Unit, University of Leicester School of Biological Sciences, in specimen preparation.     

‘Waldsterben’, part IV (continuing series)

Summary Peroxidase and superoxide dismutase activities, and ascorbic acid content, were measured in both intercellular fluid and cell material of current and 1-year-old needles of Norway spruce saplings treated with ozone, ambient air and activated carbon-filtered air in outdoor fumigation chambers. Ethylene evolution was also compared. Plants from carbon-filtered air treatments had significantly lower enzyme activities and higher ascorbic acid content. These changes were more marked in intercellular fluid than in cell material. Significant changes were noted at ozone levels typical of ambient air quality in a typical urban area. These results suggest the need for simultaneous screening of several biochemical markers as a way of overcoming the lack of specificity of any single marker for the identification of a perturbation by a particular stress, such as ozone.Acknowledgments. This work was supported in part by Grant Number 4849-0.85 (NFP 14) from the Swiss National Fund of Scientific Research. We thank Dr. F. Cupelin and Dr. J. Cl. Landry from the Service d'Ecotoxicologie, Genève, who provided the facilities for the monitoring of ozone levels. We also thank A. Mesrobian, A. Rossier and D. Voluntaru for technical assistance. Du Pont de Nemours International is gratefully acknowledged for the gift of TEDLAR (polyvinyl fluoride film) to build up the fumigation chambers.     

Effect of ascorbic acid on pigmentation of toad (Bufo melanostictus).

Administration of ascorbic acid in toad during breeding season results an increase in melanin pigments in skin, liver and vocal sac.     

A rat mutant unable to synthesize vitamin C

A colony of Wistar rats with a hereditary defect in L-ascorbic acid-synthesizing ability was established. This rat, like primates and guinea pigs, lacks L-gulonolactone oxidase (EC 1.1.3.8) which catalyzes the last step of L-ascorbic acid biosynthesis. When L-ascorbic acid was added to their drinking water, the rats grew almost normally and were fertile. These mutant rats should be useful not only for nutritional and pharmacological studies on vitamin C, but also for genetic studies on the lack of this enzyme.     

Utilization of ascorbic acid during post-embryonic development of chick skeletal muscle.

Ascorbic acid is utilized during the post-embryonic differentiation of skeletal muscle fibres in chick. While the fibres lose their heterogeneity with regard to ascorbic acid, they continue to exhibit differences in their metabolic rates in terms of the succinate dehydrogenase activity throughout life.     

Vitellogenesis in the air breathing fish,Channa punctatus (Bloch)

Summary Two types of yolk develop in the oocyte ofChanna punctatus. The carbohydrate yolk, which develops from the material present in the ooplasm, breaks up for the use of the growing oocyte before ovulation takes place. The proteid yolk, developing from the extraoocytic material, finally crams the fully mature oocyte, perhaps to participate in the process of embryogenesis.Acknowledgments. The authors are grateful to Professor C.C. Das, for his encouragement and the laboratory facilities. The award of a U.G.C. junior fellowship to one of us (U.R.A.) by the Berhampur University is thankfully acknowledged.     

Increase in acid phosphatase activity during fertilization of a teleost egg

Summary Acid phosphatase activity was localized at the periphery of the yolk globules in the egg of the teleost,Catostomus commersoni. In addition, a 3-fold increase in acid phosphatase activity was associated with fertilization and pronucleus formation.I thank Dr C. W. Huver for use of facilities.     

Spermatozoid-attracting substance in hermaphrodite brown algae,Pelvetia wrightii andFucus evanescens

Summary A spermatozoid-attracting substance of the hermaphrodite brown algae,Pelvetia wrightii andFucus evanescens, was identified as 1, trans-3, cis-5-octatriene, respectively, by¹H-NMR and¹³C-NMR data and biological activities.Acknowledgments. The authors would like to express their thanks to Mr A. Nishikawa for technical assistance, to Dr M. Abe (Yamagata Univ.) for valuable discussion on biological work and to Prof. Y. Sakai (Hokkaido Univ. Director of the Institute of Algological Research, Muroran) for the facilities during the investigation ofP. wrightii andF. evanescens. Financial support from the Ministry of Education Science, and Culture (Grant-in Aid for Scientific Research No. 556092) is gratefully acknowledged.     

Effect of ascorbic acid on pigmentation of toad (Bufo melanostictus)

Summary Administration of ascorbic acid in toad during breeding season results an increase in melanin pigments in skin, liver and vocal sac.Acknowledgment. The authors' thanks are due to Prof.C. Deb, Head of the Department of Physiology, Calcutta University, for encouragements.     

The chromosomes ofPasseromyia heterochaeta Villeneuve (Muscidae: Diptera)

Summary The 2 n=10 complement ofPasseromyia heterochaeta Villeneuve consists of 4 pairs of metacentric chromosomes and 1 pair of dots. The evolutionary implications of 2 n=10 in the tribe Phaoniini (Fam. Muscidae) are discussed.Acknowledgments. Thank are due to Dr Adrian C. Pont of British Museum (Natural Histoty), London for identifying our speciens through the courtesy of Dr Rokuro Kano, Dean Faculty of Medicine, Tokyo Medical and Dental University Tokyo, Japan. We also thank Dr U.S. Srivastava, Professor and Head, Dept. of Zoology, Univ. of Allahabad for providing the necessary laboratory faclities.     

Method for long term delivery of soluble agents to the chick chorioallantoic membrane

Summary Osmotic minipumps were used to administer thyroxine to the chick embryo. This technique proved to be a convenient and efficacious method for the delivery of soluble agents to the chorioallantoic membrane. The thyroxine induced the precocious appearance of extensive cell sloughing by the corneal epithelium.     

Latent differentiation in the endoderm of the young chick embryo]

Initiation and localization of the capacity of self-differentiation in the 1-2 day old chick embryo were studied by means of culturing endoderm fragments, wrapped in a piece of viteline membrane and completely deprived of mesenchyme.