Choline acetyl transferase activity in chick embryo neuroretinas during development in ovo and in monolayer cultures

The specific activity of the enzyme choline acetyl transferase (CAT) in chick neuroretinas was investigated during in ovo development and in monolayer cultures. The enzyme activity was barely detectable on the 6th day of incubation but increased markedly between the 7th and 11th days. The activity increased sharply between the 15th and 17th days and then slowly until hatching. When cell suspensions from 6- to 7-day neuroretinas were cultured as monolayers, CAT specific activity increased rapidly. After 4–5 days in culture, the activity of the enzyme was identical to that found in the neuroretina on the 11th day of incubation. Cells from 9-day neuroretinas also differentiate in monolayer cultures, but with a more irregular pattern. These data show that cholinergic neurons from chick embryo neuroretina differentiate in monolayer cultures without a lag and at the same rate as in vivo.     

Du probleme de l'origine des Dinosauriens d'apres les donneesde l'ichnologie du Trias

With the data of the osteological paleontology and these of the ichnology, the authors attempt to restore the biotopes where lived the trackmakers, biotopes which have favoured in the Triassic the evolution and the expansion of the Archosaurs, the specialized Reptiles in the easy and rapid locomotion. They pointed out that the chirotheroid footprints cannot be attributed at all events to the Pseudosuchians and they come to the conclusion that Dinosaurs and Pseudosuchians, as separated groups, are appeared as early as the lower Triassic.     

Stimulation in rat DMBA-mammary tumours of the synthesis of a protein similar to the oestrogen-induced protein of the rat uterus [proceedings].

The induction by estradiol-17beta (E2) in DMBA-induced mammary tumors of a protein similar to that found in the uterus of estrogen-treated rats is reported. It is called an indirect protein (IP) and was demonstrated by an increased incorporation of labeled amino acids in a specific band of polyacrylamide gel electrophoresis. All the tumors contained the receptor for estrogen. A definite IP peak was shown by using a cytosol mixture that was enriched in the IP fraction by precipitation with 80% ammonium sulphate before electrophoresis. Data indicate that IP may represent a basic feature of target tissue response to estrogen stimulation. Measurement of IP synthesis might offer a method for investigating estradiol dependence.     

Capacités reproductrices et descendance de poulets ayant subi un transfert de cellules germinales primordiales durant la vie embryonnaire

Résumé Des cellules germinales primordiales de Dindon, transférées par injection intravasculaire à des embryons de Poulet préalablement stérilisés, peuvent subir une maturation complète dans les gonades de l'hôte et fournir des gamètes plus ou moins aptes à la fécondation.Les spermatozoïdes résultants ont fécondé des oeufs de poule avec une fréquence plus grande que les spermatozoïdes normaux de Dindon, mais sans permettre un développement embryonnaire plus important ou plus normal. Cependant, on n'est pas parvenu à leur faire féconder des oeufs de dinde.Les ufs résultants ont montré parfois un vitellus anormal et n'ont été pondus que durant 7 mois. Mis en présence de spermatozoïdes de coq, ils ont été quelquefois fécondés (ou peutêtre simplement activés), mais ils n'ont jamais fourni d'embryons. Fécondés par des spermatozoïdes de Dindon, ils ont fourni des embryons, parfois anormaux, qui ont atteint dans le meilleur cas le 15è jour d'incubation (stade 38 HH). Certainespraepennae de l'embryon qui a atteint ce stade montraient une pigmentation rouge brun qui ne peut pas être déterminée par le génotype du zygote (celui d'un Dindon de race blanche) et qui rappelle le phénotype de la mère nourricière (une poule rouge brun).A la suite de transferts intraspécifiques de cellules germinales primordiales, on a pu obtenir la maturation d'ovocytes de Rhode Island Red à l'intérieur d'un ovaire de Wyandotte Blanche (chez deux poules) et vice versa (chez une poule). La ponte a également été possible, mais à une fréquence souvent inférieure à la normale.Lorsqu'une poule Wyandotte Blanche, portant des ovocytes de Rhode Island Red a été accouplée à un coq Rhode Island Red normal, le duvet de leurs descendants s'est montré plus clair que celui des poussins Rhode Island Red dans un cas, mais il a été remplacé ensuite par un plumage rouge brun conforme au génotype.Lorsqu'une poule Rhode Island Red, portant des ovocytes de Wyandotte Blanche a été accouplée à un coq Wyandotte Blanche normal, le duvet de leurs descendants n'a jamais été conforme au génotype. Il présentait toujours du pigment noir plus ou moins étendu et, dans un cas, du pigment rouge brun, qui sont tous deux présents chez la mère nourricière. On ne connaît ni l'origine ni le mécanisme d'un tel transfert de pigments, qui ne représente peut-être qu'un effet transitoire affectant le duvet de la première génération. La crête, quant à elle, s'est toujours montrée conforme au génotype d'origine.

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Reproductive capacity and offspring of chickens submitted to a transfer of primordial germ cells during embryonic life

Summary Turkey primordial germ cells transfered by intravascular injection to previously sterilized chick embryos can undergo complete maturation inside the host's gonads and can give rise to gametes which are more or less suitable for fertilization.The resulting spermatozoa fertilized hen eggs at a higher frequency than normal turkey spermatozoa, but without allowing a longer or a more normal development. However, it was impossible to fertilize turkey eggs with them.The resulting eggs sometimes had an abnormal-looking yolk and were laid during the first 7 months only. Brought in contact with chicken spermatozoa, they were fertilized (or perhaps merely activated), but they never gave rise to embryos. Fertilized by turkey spermatozoa, they developed into embryos, sometimes abnormal, which in the best case reached the 15th day of incubation (stage 38 HH). Somepraepennae of the latter embryo showed a red-brown pigment which cannot be determined by the genotype of the zygote (a white turkey's) and which resembled the phenotype of the foster mother (a red-brown hen).After intraspecific transfer of primordial germ cells, maturation of Rhode Island Red oöcytes inside a Wyandotte White ovary (in two hens) and vice versa (in one hen) was achieved. Laying was also possible but often at a lower frequency than normal.When a Wyandotte White hen bearing Rhode Island Red oöcytes was mated with a normal Rhode Island cock, the down of their offspring looked brighter than Rhode Island Red chicken's in one case, but it was subsequently replaced by red-brown feathers according to the genotype.When a Rhode Island Red hen bearing Wyandotte White oöcytes was mated with a normal Wyandotte White cock, the down of their offspring was never in agreement with the genotype. It always showed a black pigment over more or less large areas and, in one case, a red-brown pigment, both of which were present in the foster mother. The origin and the mechanism of such a transfer of pigments are not understood. It might represent merely a temporary effect acting upon the down of the first generation. As far as the comb is concerned, it was always in agreement with the original genotype.

     

Pituitary and extrapituitary effects of somatostatin in normal man.

The effects of synthetic linear somatostatin on basal circulating levels on several pituitary and pancreatic hormones, and of glucose and free fatty acids (FFA) were studied in 6 normal men after an overnight fast. A priming intravenous infusion of 250 mug of somatostatin in 18 sec was followed by a constant infusion of 500 mug over a period of 60 min. A decrease in plasma values of GH, prolactin, TSH, insulin and glucagon and in blood glucose was observed during somatostatin infusion, while FFA levels increased progressively. Plasma IRI and blood glucose increased rapidly when the somatostatin infusion was stopped, while FFA decreased progressively; GH, prolactin, TSH and glucagon remained low as compared to basal levels for one hour after the end of the infusion, i.e. until the end of the experiment. A slight but significant increase of LH and ACTH was observed after the end of the infusion.     

Physiological and pharmacological effects of estrogens in breast cancer.

Focus here is on the mechanism of action of both estrogens and antiestrogens at the tumor cell levels in breast cancer. The interactions of estrogens and their antagonists are emphasized and analyzed in terms of current and potential clinical applications to breast cancer treatment. This review deals with these interrelationships at the molecular levels, not just with general aspects of endocrine interrelationships. The article is divided into 8 main parts: 1) an introduction, which reviews historical understanding of receptor technology and significances; 2) main properties of estrogens and estrogen receptors; 3) the influence of estrogens and antiestrogens on growth of experimental mammary tumor systems; 4) the suppression of or administration of estrogens for treatment of advanced human breast cancer; 5) estrogen receptivity of mammary tumors; 6) progress in treatment of advanced breast cancer derived from studies on the mode of action of estrogens; 7) the prognostic significance of estrogens and estrogenic receptivity (the estriol theory); and 8) concluding remarks on the future paths of receptor research.     

Lack of Liver X Receptors Leads to Cell Proliferation in a Model of Mouse Dorsal Prostate Epithelial Cell

Recent studies underline the implication of Liver X Receptors (LXRs) in several prostate diseases such as benign prostatic hyperplasia (BPH) and prostate cancer. In order to understand the molecular mechanisms involved, we derived epithelial cells from dorsal prostate (MPECs) of wild type (WT) or Lxrαβ−/− mice. In the WT MPECs, our results show that LXR activation reduces proliferation and correlates with the modification of the AKT-survival pathway. Moreover, LXRs regulate lipid homeostasis with the regulation of Abca1, Abcg1 and Idol, and, in a lesser extent, Srebp1, Fas and Acc. Conversely cells derived from Lxrαβ−/− mice show a higher basal phosphorylation and consequently activation of the survival/proliferation transduction pathways AKT and MAPK. Altogether, our data point out that the cell model we developed allows deciphering the molecular mechanisms inducing the cell cycle arrest. Besides, we show that activated LXRs regulate AKT and MAPK transduction pathways and demonstrate that LXRs could be good pharmacological targets in prostate disease such as cancer.