In vitro development ofXenopus skin glands producing 5-hydroxytryptamine and caerulein

The granular glands of amphibian skin synthesize and store a large amount of bioactive amines and peptides which are structurally similar to mammalian brain-gut peptides. To investigate the development of peptide- and amine-producing cells in the granular glands, pieces of dorsal skin taken at various stages fromXenopus laevis tadpoles were cultured, and the contents of caerulein and 5-hydroxytryptamine (5-HT) were measured. When pieces of skin from tadpoles at stages 57 to 60 (Nieuwkoop and Faber stages) were cultured in a medium containing 10% fetal calf serum (FCS medium) or one containing FCS treated with charcoal (chFCS medium), the caerulein and 5-HT levels were increased for the six days of the incubation period. The caerulein content was lower in the chFCS medium than in the FCS medium. Addition of thyroxine to the chFCS medium had no significant effect on the caerulein content. These results show that the caerulein-and 5-HT-producing cells of the granular glands can develop in a culture system with FCS- or chFCS-containing media, and suggest that FCS contains substances which are absorbed by charcoal and stimulate development of the amine- and peptideproducing cells of the glands. In a preliminary search for correlation between caerulein and 5-HT synthesis, addition of 5-hydroxytryptophan (5-HTP), a precursor to 5-HT, to the FCS medium increased 5-HT content and, conversely, caused significant decrease in caerulein content, suggesting that accumulation of caerulein in the granular glands is influenced by the amount of 5-HT synthesis. These studies indicate that this culture system is a useful model for investigating the development of peptide- and amine-producing cells.     

The effect of tolbutamide on early embryos ofXenopus laevis

Summary The effect of tolbutamide on the early development of Xenopus laevis has been studied. The results suggest that continuous exposure to 3×10^–4 M tolbutamide causes abnormal development.Acknowledgments. I wish to thank Mr F. Schaefer who prepared the histological material, and Hoechst U.K. Ltd for their gift of tolbutamide.     

The investigation ofXenopus laevis hemoglobins during development by a fluorescent antibody

Zusammenfassung BeiXenopus laevis findet man im Kaulquappenstadium 2 fötale Hämoglobine (HbF) und nach der Metamorphose 3 neue Hämoglobine (HbA) vom Erwachsenentypus. Immunofluoreszenz-Untersuchungen lassen erkennen, dass während der Metamorphose keine oder nur wenige Erythrozyten gleichzeitig HbF und HbA enthalten.     

Experimentally produced ependymal inclusions in the brain ofXenopus laevis

Zusammenfassung Verletzungen des Endhirns beim erwachsenen Krallenfrosch (Xenopus laevis) führen zur Entstehung von Ventrikelteilen, die vollständig oder teilweise vom Ventrikelsystem des Gehirns isoliert sind. Das Ependym solcher Ventrikelteile zeigt stark Chromhämatoxylin-positive cytoplasmatische Einschlüsse (GPI), die im Perikaryon und in den Zellfortsätzen der Tanycyten lokalisiert sind. Charakter und Bedeutung der GPI werden diskutiert.     

Chromatin organization within nuclear blebs in leukocytes ofXenopus laevis

Summary The nuclei from leukocytes of peripheral blood, liver and spleen of an individual anaemicXenopus laevis have been found to possess numerous nuclear blebs or projections. These structures were found to be very variable in size and shape as viewed in electron micrographs, but commonly included an enclosed mass of cytoplasm bound on one side by a very thin section of nuclear material. Such sections are membrane bounded on each side and frequently display an interesting ordered array of chromatin.     

Pronephric system in haploid and diploid larvae ofXenopus laevis

Zusammenfassung Eine morphologische Untersuchung des Vornierensystems in haploiden und diploiden Xenopuslarven weist darauf hin, dass das haploide Oedem nicht durch eine Funktionsstörung des Vornierensystems verursacht ist.     

The location of soluble antigen in the spleen ofXenopus laevis

Résumé Une étude de la localisation de -globulines humaines (en solution saline) dans la rate deXenopus laevis a été effectuée en utilisant la fluorescence pour la détection d'antigènes. La thymectomie n'a eu aucun effet sur la première apparition d'antigènes dans la pulpe rouge entourant la zone de pulpe blanche.

---

---

This work was supported by a Science Research Council Studentship. The author thanks Dr.M. J. Manning for advice and criticism.     

Long term retention of colloidal thorium dioxide in the liver and spleen ofXenopus laevis daudin

Résumé Des observations ultrastructurales ont montré que le thorium bioxyde colloïdal (ThO₂) s'accumule dans le foie et la rate des grenouilles,Xenopus laevis, jusqu'à 3 ans après une seule injection de 10 mg pratiquée sur le jeune animal, 6 mois après sa métamorphose.     

Inbreeding effect: embryonic development and fecundity of Drosophila melanogaster offspring.

Inbreeding depression observed on fecundity of adult Drosophila depends on the effect observed during development of the eggs laid by their parents. This depression does not then depend on the homozygosity per se of the adult genome. It is mainly due to the deleterious effect observed primarily during embryogenesis.     

High affinity binding of 5-hydroxytryptamine to some membrane preparations from cattle brain. Relationship to lysergic acid diethylamide (LSD)]

5 hydroxytryptamine binds to crude brain membrane preparations with two different affinities (KD = 1 to 2 X 10(-9) M for the highest, 1 to 2 X 10(-8) M for the lowest). LSD also binds with two affinities (KD = 3 to 4 X 10(-9) M and KD = 2 to 3 X 10(-8) M). Subcellular distribution of these sites shows that binding involves the two binding affinities in microsomal membranes but solely the high affinity binding sites are present in purified synaptosomal membranes. High affinity sites for 5 HT and for LSD are different as no direct competitive inhibition is observed in that case. On microsomal membranes, direct relationship occurs between low affinity binding for 5 HT and high affinity binding for LSD.     

Difference in the response to PIF/activin between animal caps excised from mid- or late blastula stages ofXenopus laevis

Animal caps fromXenopus embryos at Stage 7/8 cultured in salt solution, were capable of elongating, and formed various embryonic tissues including axial mesoderm, nervous tissues and pigmented retina. In contrast, animal caps from Stage 9 only developed into permanent blastulae. Following exposure to PIF/activin, however, such animal caps displayed morphogenetic movements. They formed tube-shaped embryoids that frequently had one or more tails but no head. We conclude that animal caps from Stage 9 produce more reliable results than those from Stage 7/8 because the latter are most likely contaminated with mesodermal cells.     

Human platelet 5-hydroxytryptamine receptors: binding of [3H]-lysergic acid diethylamide (LSD). Effects of chronic neuroleptic and antidepressant drug administration

Chronic treatment with phenothiazines and thioxanthenes has been found to enhance 5-HT-induced aggregation of human platelets. A method has been developed to study 5-HT2 receptor binding sites on platelets utilising [3H]-LSD and more recently 125I/LSD. Results are presented which suggest that the LSD binding site is indeed the 5-HT2 binding site and that the LSD binding characterises the specific receptor responsible for 5-HT-induced shape change and aggregation. In a group of patients receiving phenothiazines or thioxanthenes, the Bmax of LSD binding was increased. The mean binding affinity was decreased possibly due to a persistence of neuroleptic in the platelet membrane preparation. Analysis showed that this was not the reason why the mean binding capacity was increased. The results show that chronic phenothiazine and thioxanthene delta treatment 'up-regulates' platelet 5-HT2 binding sites and that this may be accompanied by increased sensitivity to platelet aggregation by 5-HT. In normal subjects desipramine treatment increased the Bmax of platelet LSD binding and this was accompanied by an increased prolactin response to tryptophan which is thought to be mediated by central 5-HT function.     

Occurrence of 5-hydroxytryptamine in chick retina

Summary 5-Hydroxytryptamine (5-HT) was found in chick retina. 5-HT level in chick retina was increased by the administration of pargyline and decreased by reserpine, but remained unchanged with tryptophan.     

Possible 5-hydroxytryptamine component in the effect of apomorphine in isolated cerebral and peripheral arteries

Summary The effect of apomorphine was studied in isolated perfused rabbit arteries contracted by high potassium concentrations. The influence of methysergide suggests that apomorphine responses in central ear arteries, but not in middle cerebral arteries, are partially mediated by serotonin receptors.     

Storage of 5-hydroxytryptamine in human blood platelets

Zusammenfassung Menschliche Blutplättchen zeigten die höchste 5-Hydroxytryptamin (5HT)- und Adenosin-5-Triphosphat (ATP)-Konzentration in einer subzellulären Fraktion, die elektronenoptisch aus Vesikeln von unterschiedlicher Dichte bestand. Diese waren deutlich verschieden von anderen subzellulären Organellen, z.B. den -Granula. Inkubation der Plättchen mit 5 HT erhöhte die Elektronendichte und den 5 HT-Gehalt der Vesikel, veränderte aber die -Granula nicht, Es wird geschlossen, dass in menschlichen Blutplättchen ein Teil des 5 HT zusammen mit ATP in spezifischen subzellulären Organellen gespeichert ist.