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.     

Juvenile hormone I is the principal juvenile hormone in a hemipteran insect,Riptortus clavatus

Juvenile hormone I (JH I) was identified by combined gas chromatography/mass spectrometry as the predominant JH in the hemolymph of female adults of the bean bug,Riptortus clavatus (Thunberg) (Hemiptera: Alydidae). Among JH I, II, and III, JH I was the most effective hormone for inducing the synthesis of yolk proteins in diapause adults.     

Explantationsin vitro de blastodermes de Poissons(Salmo,Esox)

Summary Blastula of trout (Salmo irideus) and pike (Esox lucius), deprived of their yolk, are cultivated in the Holtfreter solution. The differenciation of the germ of the trout stops; that of the pike germ is carried on almost normally. That difference might be due to the influence of nucleic acids contained in it.     

Immunochemical identification of vitellogenin in the serum of the newtTriturus cristatus

Summary The hematic yolk precursor — vitellogenin — has been identified immunochemically in the serum of estrogenized females of the newtTriturus cristatus by employing an antiserum prepared against yolk proteins.     

Mitocondri,zone del Golgi e globuli vitellini negli ovociti in accrescimento diPlanorbis corneus L. (Moll. Gast. Polm.)

Summary The authors observed, in the oocytes ofPlanorbis corneus, that the yolk globules are formed from the mitochondria, which first swell up and then are filled with proteic particles (of a probably ribosomal nature). Such a process is in relation to the formation of the Golgi zones.     

Acid phosphatase in eggs of the zebrafish,Brachydanio rerio

Summary 2 isozymes of acid phosphatase have been identified by polyacrylamide disc gel electrophoresis in the ovary and mature, unfertilized eggs ofB. rerio. Histochemically, the enzyme appears to be localized in preyolk bodies of previtellogenic oocytes and in yolk platelets of vitellogenic and postvitellogenic oocytes. The contents of the cortical granules at all stages of oocyte differentiation were acid phosphatase negative.     

Methods of experimental yolk removal fromBrachydanio rerio eggs

Summary The yolk ofBrachydanio rerio eggs was removed by pipettation, bursting and cutting off with a scalpel. The total yolk removal before the 8-cell stage led to a germ with irregular groups of cells, at the 8-cell stage to a topologically irregular differentiation, at the 64-cell stage to a nearly normal embryo, which is not viable.     

On the origin of the protein yolk in the oocytes ofAplysia depilans (Gastropoda,Opistobranchia)

Summary In the oocytes ofAplysia depilans it has been observed electronmicroscopically that gemmae or daughter-nucleoli separate from the nucleolus. These gemmae after having overcome the nuclear membrane, would aggregate together, even after transformation, into yolk globules. These observations seem to give plausibility to the hypothesis that there is a close relationship between production of ribonucleoproteic material by the nucleolus and yolk production.     

La vitellogenesi inArbacia lixula eSphaerechinus granularis (Echin. Echin.)

Summary The researches carried out both under the light and electron microscopes permitted us to ascertain that, in EchinodermataArbacia lixula andSphaerechinus granularis, yolk globules form by aggregation of ribonucleoproteic particles. It appears that the globules themselves in the first stage of their formation show such physico-chemical conditions as to condition the precipitation of silver in the method used to reveal Golgi apparatus.     

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.     

Histopathological effect of thiourea on the ovarian tissues ofSarcophaga ruficornis (Fabr.)

Summary The primary target of thiourea in femaleSarcophaga are the follicles in the ovarioles. The follicle cells as a result become syncytial and their nuclei get pycnotic, inhibiting the transport of nutrient material into the nurse cells and of yolk into the oocytes. The subnormal eggs produced are not viable.     

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     

Development of an enzyme linked immunosorbent assay (ELISA) for measurement of vitellogenin concentrations in cockroaches

Summary A competitive enzyme linked immunosorbent assay was developed for the quantification of a large lipoprotein, namely the yolk protein vitellogenin, in the haemolymph of cockroaches (Nauphoeta cinerea). This assay was found to be specific, reproducible and it has a high sensitivity (approximately 10 ng).Acknowledgments. We would like to express our thanks to Prof. H. Fey and Ms H. Pfister, Veterinary Bacteriological Institute, University of Berne, for introducing us into the ELISA methodology, to P. Beyeler for technical assistance and to M. Kaltenrieder for drawing the graphs. We also thank the Sandoz Foundation for a fellowship to M. Dumas and the Swiss National Science Foundation (grant No. 3. 188-0.77) for financial support.     

A possibility to achieve genetic transformation in the platyfish-swordtail system (Platypoecilus maculatus — Xiphophorus helleri)

Summary In order to determine how informative homologous donor DNA might be made available to propigment cells of the recipientXiphophorus helleri for transformation, labelled heterologous DNA fromE. coli was injected into the neural crest region or the yolk sac of embryos of the recipient. On the basis of the degradation rate of the donor DNA and the incorporation rate of radioactivity into the recipient DNA, it is concluded that injection into the neural crest region may be a suitable method to make available informative homologous donor DNA for transformation.Supported by DFG through SFB No. 103, and by Stiftung Volkswagenwerk.     

Is there really actin aroundXenopus laevis yolk platelets

Summary Our previous immunofluorescence experiments (1) on actin localization in Xenopus development showed a fluorescent halo around Xenopus yolk platelets. This fact suggests the presence of a sort of actin covering of the yolk platelet; we have called this structure the actin-shell. In this work, by the use of a DNase I-fluorochrome complex, we were able clearly to demonstrate the presence of the actin-shell around Xenopus yolk platelets. A proposal about the function of the actin-shell is made; its presence could mark the difference between autosynthetic and heterosynthetic eggs.This study was supported by grant CT 80.00480 from Consiglio Nazionale delle Ricerche, Roma, Italy.     

Yolk protein differences between species ofDrosophila

Summary 1–3 major proteins considered as vitellins or yolk proteins are detected in mature eggs from differentDrosophila species by gel electrophoresis on gradient slab gels. Qualitative and quantiative differences are found even between closely related species. In heteroplastic transplantations, no correlation was found between the similarity or dissimilarity of the protein pattern on the one hand, and success of failure of egg development and vitellogenesis on the other hand.We thank Mr B. Barandun for excellent technical assistance. This investigation was supported by the Swiss National Science Foundation, grant No. 3.792.76.     

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.     

Distribuzione di fosfatasi alcaline in gonadi di Crostacei isopodi in rapporto al ciclo degli acidi nucleici

Summary The distribution of alkaline phosphatases has been studied in male and female gonads of some isopod crustaceans by means of Gomori's reaction.Monophosphatases are found on all Feulgen-positive nuclear structures, in the nucleolus and in the cytoplasm of young oocytes. They disappear from the cytoplasm in auxocytosis, during yolk formation, although they persist in the germinal vesicle. The authors think that the cytoplasmic localization is coincident with ribonucleic acid distribution.From the experiments related in the following note, nucleolar phosphatases appear to be in some way different from the nuclear (sensu stricto) and cytoplasmic phosphatases.Diphosphatases do not follow so closely the nucleic acid localization. They are absent from cytoplasm; in the nucleolus they are not distributed uniformly but show characteristic structure; in the nucleus they are not localized in the chromosomes but homogeneously diffused.     

Biosynthesis of ascorbic acid in chick embryos

Summary 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.I am grateful to Dr R. Jenness (Univ. of Minnesota) for the generous gift of L-gulonolactone and to Dr B. Sanders (Univ. of Texas) for the chick embryo samples     

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.