scispace - formally typeset
Search or ask a question

Showing papers by "Utrecht University published in 1970"


Journal ArticleDOI
TL;DR: In this paper, a comparison of massive and mass-less theories with experiment, in particular the perihelion movement of Mercury, leads to the exclusion of the massive theory and it is concluded that the graviton mass must be rigorously zero.

1,201 citations


Journal ArticleDOI
TL;DR: A significant difference in toxicity was found between the compounds: compounds I and II showed the highest, compound III the lowest, toxicity.

167 citations


Journal ArticleDOI
TL;DR: In Apis mellifera melliferA the ovary of a worker bee possesses on the average three to five ovarioles, although the maximum number may be much higher (up to 21).
Abstract: In Apis mellifera mellifera the ovary of a worker bee possesses on the average three to five ovarioles, although the maximum number may be much higher (up to 21). The development of the ovaries is influenced by several environmental factors and by innate factors as well. One of these innate factors is the number of ovarioles. In an experimental population of 50 the bees with the most highly developed ovaries have an inhibitory effect on ovarian development in the other bees. Resume DEVELOPPEMENT DE L'OVAIRE CHEZ LES OUVRIERES D'APIS MELLIFERA Le degre de developpement des ovaires chez les ouvrieres peut etre un moyen d'apprecier la dominance de la reine et d'etudier la differenciation des castes. C'est dans cet esprit que ce travail a ete entrepris, il a conduit aux remarques suivantes: 1 – Le nombre d'ovarioles par ovaire se repartit selon une courbe de frequence dissymetrique. La moyenne arithmetrique du nombre d'ovarioles, pour des ouvrieres de 5 colonies, est comprise entre 3,8 et 5,1; le nombre le plus frequent est 3 ou 4, et le nombre maximum varie de 8 a 15. 2 – Le degre de developpement de l'ovaire peut etre estime d'apres l'etat de differenciation et de croissance des ovocytes (ovogenese) (fig. 2). 3 – Les facteurs qui influencent le developpement de l'ovaire sont etudies, Parmi ceux-ci il faut signaler l'influence saisonniere et l'effet d'un eclairement continu. 4 – On a etabli qu'il existe une correlation cntre le nombre d'ovarioles et le degre de developpement de l'ovaire. 5 – Le probleme de l'inhibition du developpement de l'ovaire en presence d'ouvrieres pondeuses est aborde. Les experiences realisees mettent en evidence ce role inhibiteur.

164 citations


Journal ArticleDOI
TL;DR: It could be tentatively concluded that the susceptibility of the 1-acyl ester bond to lipase is influenced by the type of bond present at the 2-position, similar to that of phosphatidylcholine.

118 citations


Journal ArticleDOI
TL;DR: The small3H/14C ratios observed in 3-sn-phosphatidylcholine and phosphatidylethanolamine allow the conclusion that, at least under these conditions, the uptake of fatty acids into these phospholipids proceeds mainly via acylation of their mono-acyl derivatives.

110 citations


Journal ArticleDOI
TL;DR: In this article, the triton binding energy, doublet scattering length, Coulomb energy, and S′ -and D -state probabilities are determined within the framework of the Faddeev equations.

100 citations


Journal ArticleDOI
TL;DR: Results clearly show that the atretio follicle of the Guppy does not produce steroid hormones, and it is preferable to use the name Corpus atreticum instead of Corpus luteum praeovulationis.

84 citations


Journal ArticleDOI
TL;DR: The results obtained allowed the conclusion that both choline- and ethanolaminephosphotransferase show no specificity with respect to the nature of the diacylglycerol molecule, at least for the species tested so far.

75 citations


Journal ArticleDOI
TL;DR: In this article, the dynamics of the diffuse liquid-gas interface near the critical point is studied and the dispersion equation for surface waves is derived and it is shown that the surface tension appearing in the dispersive equation is correctly given by van der Waals's expression for the surface free energy of the equilibrium interface.

74 citations


Book ChapterDOI
TL;DR: The behavioral effect of ACTH could be studied in intact animals independently of concomitant steroid action, and α- and β -melanocyte stimulating hormone (MSH), which exert a similar inhibiting effect on extinction of conditioned avoidance behavior as ACTH, also share the amino acid sequence that is known asACTH.
Abstract: Publisher Summary Adrenocorticotropic hormone (ACTH) and corticosteroids exhibit an opposite effect on extinction of conditioned behavior in studies that were designed to elucidate the roles of the separate hormones: ACTH can inhibit extinction of conditioned avoidance behavior, while glucocorticosteroids—and some other steroids as well—can facilitate the rate of extinction. The study of the effects of ACTH on the behavior of intact animals received a new impetus after the discovery that fragments of this hormone containing the first 10 amino acids—or even smaller peptides such as ACTH-(C10)—could still exhibit a similar behavioral effect as ACTH. These peptides lack the well-known biological activities of the intact hormone such as stimulation of the adrenals. The behavioral effect of ACTH could be studied in intact animals independently of concomitant steroid action. Labeling these peptides as “ACTH-analogues” is more a matter of habit than of precise description because α- and β -melanocyte stimulating hormone (MSH), which exert a similar inhibiting effect on extinction of conditioned avoidance behavior as ACTH, also share the amino acid sequence that is known as ACTH.

64 citations


Journal ArticleDOI
TL;DR: Results clearly show that the atretio follicle of the Guppy does not produce steroid hormones, and it is preferable to use the name Corpus atreticum instead of Corpus luteum praeovulationis.
Abstract: The problem of the endocrine significance of the atretic follicle in the ovary of fishes has been approached with histological and cytological methods in the Guppy, Poecilia reticulata. The atretic follicles are subdivided into four stages: α-, β-, γ-, and δ-stage. During the period of pregnancy, lasting approximately one month, the atretic follicles were irregularly present. In 50 out of 73 animals, they were entirely absent. This appeared to have no influence upon a normal pregnancy; consequently, endocrine activity of the atretic follicle is not probable. The results of the cytochemical test also pointed in this direction. Enzymes, essential for steroid synthesis could not be proved to be present. Acid phosphatase and E-600 resistant esterase, however, were found in considerable amounts, indicating the presence of lysosomal activity. These results clearly show that the atretio follicle of the Guppy does not produce steroid hormones. Consequently, it is preferable to use the name Corpus atreticum instead of Corpus luteum praeovulationis. Moreover, it appears from cytochemical results that the degeneration process of the follicle can be subdivided into two phases: primarily the resorption of the oocyte during the α-stage, and secondly the regression of the granulosa cells during the subsequent stages.

Journal ArticleDOI
TL;DR: The secretion of the mandibular glands of a honey bee queen enables the worker bees to react to the presence of their queen and supports Verheijen-Voogd's (1959) conclusion that the queen's influence on her workers has a behavioural basis (chemoreception) rather than a biochemical one.
Abstract: The secretion of the mandibular glands of a honey bee queen enables the worker bees to react to the presence of their queen. Extirpating the mandibular glands of the queen does not prevent that she is accepted by her colony. Hitherto this was attributed to contamination of the queen's body by mandibular gland substances during or preceding the extirpation. When, however, these glands are extirpated before they have secreted any material and the queens are inseminated artificially, the colonies still accept these queens. A normal-sized retinue, the absence of emergency cell building and the absence of activation of the worker's ovaries indicate that such a queen is still able to maintain her social position. This supports Verheijen-Voogd's (1959) conclusion that the queen's influence on her workers has a behavioural basis (chemoreception) rather than a biochemical one.

Journal ArticleDOI
06 Jun 1970-Nature
TL;DR: Rocks of Permian age, which seemed most suitable for detecting rotations of the Southern Alps, Corsica, and the Iberian Peninsula, were collected in Sardinia in the hope of finding more conclusive evidence.
Abstract: PALAEOMAGNETIC data from Middle Tertiary rocks have not decisively shown any rotation of Sardinia1. Rocks of Permian age, which seemed most suitable for detecting rotations of the Southern Alps2,3, Corsica4 and the Iberian Peninsula5, were therefore collected in Sardinia in the hope of finding more conclusive evidence.

Journal ArticleDOI
TL;DR: In this article, the modified surface delta interaction (MSDI) was used for negative-parity states in 35 Cl, 35 S, 37 Cl, 39 Ar and 39 K. The MSDI interaction parameters as well as the single-particle binding energies have been deduced from a least-squares fit to experimentally known levels in A = 35, 37 and 39 nuclei.


Journal ArticleDOI
TL;DR: In this article, an experiment was designed in which two variations of Other's expert power and Subject's extent of participation with Other (Other being a paper stooge) were manipulated, and two hypotheses were put to test: Hypothesis One: a higher degree of expert power (availability of relevant information) of Other will result in more effective influence by Other on Subject than lower expert power.

Journal ArticleDOI
TL;DR: It is concluded that the stimulating effect of ACTH1–10 on conditioned avoidance acquisition in hypophysectomized rats is not caused by an influence on sensory capacities.

Journal ArticleDOI
TL;DR: A reproducible extraction and fractionation scheme for the isolation of peptides from nervous tissue is described and the occurrence of minor quantities of glutamylpeptides, identical with or related to known γ‐glutamyldipeptides and glutathione was indicated.
Abstract: — A reproducible extraction and fractionation scheme for the isolation of peptides from nervous tissue is described. The low molecular weight fraction, obtained by this procedure from calf brain stem tissue, was further investigated. The presence of N-acetyl-aspartic acid, N-acetyl-α-aspartylglutamic acid and pyrrolidone-2-carboxylic acid was confirmed. The occurrence of minor quantities of glutamylpeptides, identical with or related to known γ-glutamyldipeptides and glutathione, was indicated. Three hitherto unknown dipeptides α-aspartylserine, alanylphenylalanine and isoleucylleucine were identified. Mass spectrometry was used in the final structure analysis.


Journal ArticleDOI
J. Bruinvels1
TL;DR: It is concluded that noradrenaline is able to lower or raise body temperature by an action on thermosensitive receptor sites in the hypothalamus and that 5-HT does not act on these sites its hypothermie efiFect being due to an unspecific action.

Journal ArticleDOI
TL;DR: In a group experiment on olfactory sensitivity a hypothesis derived from a theory by Eysenck, predicting that introverts manifest a higher sensitivity than extraverts, and a hypothesis offered by Broverman et al., predicting that females are more sensitive than males, were tested.

Book ChapterDOI
TL;DR: The purpose of the experiments described in the chapter was to determine the relationship between structure and behavioral activity by using various chemically related steroids, and it is suggested that metabolites of progesterone are also effective in suppressing a conditioned avoidance performance of rats.
Abstract: Publisher Summary This chapter discusses the effects of steroids on the extinction of an avoidance response in rats. The effect of adrenocortical steroids on the extinction of the conditioned avoidance response (CAR) might be the result of glucocorticoid activity rather than of mineralocorticoid activity, because the effect of aldosterone on extinction is small. ACTH exhibits an opposite effect—that is, it delays extinction of the CAR. The facilitating effect of dexamethasone and corticosterone on extinction of the CAR, however, is not caused by inhibition of pituitary ACTH release because the steroids also facilitate extinction of the CAR in hypophysectomized animals. This shows that metabolites of progesterone are also effective in suppressing a conditioned avoidance performance of rats. This suggests that the effect of steroids on extinction of the CAR is not specific for adrenocortical hormones. The purpose of the experiments described in the chapter was to determine the relationship between structure and behavioral activity by using various chemically related steroids.

Journal ArticleDOI
TL;DR: Most of the subcommissural organ (SCO) cells are in contact with the ventricle of the brain as well as with the limiting membranes: the ependymal cells.
Abstract: Most of the subcommissural organ (SCO) cells are in contact with the ventricle of the brain as well as with the limiting membranes: the ependymal cells. They are able to release their aldehyde-fuchsin (AF) positive secretory substance directly into the ventricle. A small number of cells, which also contains AF positive material, is not in contact with the ventricle: the hypendymal cells.

Journal ArticleDOI
TL;DR: A phospholipase a with optimal activity at pH 7.0–8.0 was found in the membranes of rat liver lysosomes and is specific for the fatty acid at the 2-position.

Journal ArticleDOI
S. Maripuu1
TL;DR: In this paper, a reduction of the analogue to anti-analogue M1 transition strength in odd-A nuclei is obtained from core polarization if both the odd particle and the particles contributing to the core polarization have j = l + 1 2.

Journal ArticleDOI
C. R. Janssen1
TL;DR: In recent years, pollen analysis has turned increasingly from historical plant geography towards paleoecology as discussed by the authors, and more and more the main interest lies in a reconstruction of the past vegetation instead of simply floristics of a region.
Abstract: In recent years pollen analysis has turned increasingly from historical plant geography towards paleoecology. More and more the main interest lies in a reconstruction of the past vegetation instead of simply floristics of a region. Vegetation as a rule is made up of communities¹) that can be described quantitatively in terms of species composition or qualitatively in terms of structure.


Journal ArticleDOI
TL;DR: Starting from 3-sn-phosphatidylcholines carrying a 14C-labeled unsaturated fatty acid ester at the 2-position this method turned out to be very suitable for the preparation of unsaturated 14C -labeled 2-monoacyl choline phosphoglycerides.

Journal ArticleDOI
TL;DR: Suggestions for a functional relationship between hydroperoxide isomerase and lipoxygenase are discussed and the enzyme converts only 13-hydroperoxyoctadeca-cis-9-trans-11-dienoic acid, whereas the 9-Hydroperoxy isomer does not react.
Abstract: 1. The mode of action of flax-seed hydroperoxide isomerase was studied in vitro by using as substrates linoleic acid hydroperoxides formed by soya-bean lipoxygenase. 2. The enzyme converts only 13-hydroperoxyoctadeca-cis-9-trans-11-dienoic acid, whereas the 9-hydroperoxy isomer does not react. 3. The isomerization product was identified by chemical and spectroscopic methods as 13-hydroxy-12-oxo-octadec-cis-9-enoic acid. 4. 12,13-Epoxyoleic acid isomers do not act as intermediates in the isomerization reaction. 5. Suggestions for a functional relationship between hydroperoxide isomerase and lipoxygenase are discussed.

Journal ArticleDOI
11 Jul 1970-Nature
TL;DR: The first to show that PTH caused a marked and rapid increase in the rate of cyclic AMP excretion by the kidney in a parathyroidectomized rat, and a direct and rapid stimulation by PTH on adenyl cyclase in plasma membrane fractions from renal cortex.
Abstract: IT has been known for some time that cyclic AMP is involved in the action of many hormones, and investigations have included studies on the role of cyclic AMP in the action of parathyroid hormone (PTH) on kidney and bone metabolism. Chase and Aurbach1 were the first to show that PTH caused a marked and rapid increase in the rate of cyclic AMP excretion by the kidney in a parathyroidectomized rat. They also demonstrated a direct and rapid stimulation by PTH on adenyl cyclase, the enzyme responsible for the synthesis of cyclic AMP from ATP, in plasma membrane fractions from renal cortex. The same effect was found in participate fractions from embryonic rat calvaria2.