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991.
The white limestone represents a thick facies in the callovian stage of the threshold of Poitou. It makes the object of a detailed stratigraphical study which leads to its fauna and flora in the principal fossiliferous localities. The vertical range of Ammonites, layer by layer, leads to a chronostratigraphical subdivision in zones, subzones and shows up an important sedimentation break in the Upper Callovian in the axial region of the threshold of Poitou. Besides, a systematic study of plant remains gives original elements on the callovian flora in the West of France. These observations are completed by considerations of tectonic, sedimentary, paleographic and ecologic orders. 相似文献
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Eddy Roets Roger Verbeke Anne-Marie Massart-Le?n Georges Peeters 《The Biochemical journal》1974,144(3):435-446
1. A lactating-sheep mammary gland was perfused for 12h in the presence of l-[2-(14)C]-citrulline and received adequate quantities of glucose, acetate and amino acids. Two lactating-goat udders were similarly perfused in the presence of either l-[carbamoyl-(14)C,-2-(14)C]citrulline or l-[carbamoyl-(14)C,1-(14)C]citrulline and l-[4-(3)H]arginine. 2. In these experiments, [(14)C]citrulline was substantially oxidized to CO(2) and converted into arginine and proline of casein. 3. The specific radioactivities of arginine, ornithine and proline of the plasma increased after passage through the udders, demonstrating that [(14)C]citrulline is metabolized by the mammary gland. 4. The presence of two unknown radioactive metabolites of [(14)C]citrulline was detected in the perfusate. These substances were not found after incubation in vitro of oxygenated blood in the presence of the radioactive precursor. 5. From these experiments, it is concluded that citrulline is metabolized in mammary tissue by way of arginine to urea, ornithine and proline. 相似文献
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Georges Buhlmann 《Journal of insect physiology》1976,22(8):1101-1110
In the cockroach Nauphoeta cinerea the incorporation of a protein of low solubility into the oöcytes begins at day 5 of its adult life. An immunologically identical protein appears in the haemolymph two days earlier. The concentration of this protein, i.e. ‘vitellogenin’ in the haemolymph increases up to the onset of yolk incorporation into the oöcytes. During ovarian development no correlation could be detected between vitellogenin titre and several other parameters (ovary dry weight, length of the basal oöcytes, haemolymph protein concentration, body weight and age when ovulation occurred). In young females vitellogenin titre depends on the age, i.e. the volume of the corpora allata and hence on the presence and the titre of JH. During the period of egg maturation the total haemolymph protein concentration generally tends to drop while materials not precipitable by trichloracetic acid circulate at higher concentration after ecdysis and before ovulation.Early decapitation prevents vitellogenin synthesis and oöcyte growth, but when JH is applied to decapitated females, the normal vitellogenin titre is re-established, ovarian development, however, cannot be fully resumed. A dose-response curve shows that serial application of the hormone is much more effective than single large doses. Farnesylmethylester, a JH mimic, is about a hundred times less active, but more persistent than JH. Copulation seems to enhance the synthesis and release of endogenous JH, while food and water uptake are necessary to guarantee and optimal ovarian development. JH and high vitellogenin titre never restore ovarian development in females deprived of food and/or water or in those decapitated shortly after ecdysis. 相似文献
999.
Theodore M. Liszczak Georges S. Richardson David T. MacLaughlin Paul L. Kornblith 《In vitro cellular & developmental biology. Plant》1977,13(6):344-356
Summary Colonies of cells of epithelioid appearance were identified in monolayer cultures grown up to 50 days from normal human endometrial
cell suspensions obtained by a method designed to insure a maximum harvest of glandular cells. Groups of these cells were
separated from stromal cells by means of cloning cylinders. Studies comparing the ultrastructure of cells of this type to
fresh endometrial tissue revealed a number of similarities. The morphological characteristics common to both types of samples
included junctional complexes, perinuclear microfilaments and microvilli with glycocalyx. Other common features were prominent
nucleoli, well developed Golgi, rough endoplasmic reticulum and membranebound electron-dense bodies in the cytoplasm. A stripping
technique applie to the fetal bovine serum used in the nutrient medium made it possible to initiate cultures in a steroidfree
environment and to maintain them in the presence of the specified concentration of estradiol and/or progesterone. Isolation
of epithelial cells of endometrium in monolayer culture may provide a useful model system in which to study the specific effects
of steroid hormones on cellular function and differentiation.
Supported by grants from the National Institutes of Health (CA 18678 and CA 07368). 相似文献
1000.