Action of rat uterine secretion on the corona cells of the ovum and its modification by sex hormones

Résumé La ligature des extrémités distales des cornes utérines de rates castrées et sensibilisées à l'stradiol (3 g/kg/jour, s.c.) permet de recueillir au bout de 21 jours la sécrétion utérine accumulée. Celle-ci renferme un facteur provoquant in vitro la dispersion des cellules de la couronne de l'uf. Cette action est inhibée par un prétraitement de progestérone (10 mg/kg/jour, s.c.) du 14^è au 21^è jour ou par de fortes doses de testostérone. L'stradiol, par contre, ne présente pas cette action inhibitrice.     

Effect of heat on serum thyroxin and thyrotropin and its modification by dihydrotachysterol

Zusammenfassung Dehydrotachysterol (DHT 500 µg/kg/24 h) erhöht den TSH- und T-4-Spiegel in Rattenserum bei normalen und hohen Temperaturen, ohne den Calcium-Spiegel zu verändern, und verhindert den Tod von Ratten, die bei 34° oder 37°C gehalten werden. Das Überleben der Ratten nach DHT-Injektionen erklärt sich durch erhöhte T-4-Produktion, die einen negativen «Feedback» auf den Hypothalamus ausübt und so die lethale Überproduktion von TSH verhindert.

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This study was generously aided by a grant from the Dr.Gerald Kaplan family, Kfar Shmaryahu (Israel).     

Effect of diabetes on the vertebral column of rats and its modification by estradiol

Summary In vertebrae of genetically selected sucrose-fed diabetic rats a statistically significant bone deficit was found after diabetes had been present for about 8 months. No osteopenia was observed in diabetic rats following treatment with estrogenic hormone for 5–7 months. The development of osseous centers in the end plates of the vertebrae was retarded in diabetic rats, but was about normal in diabetic rats given estrogen.—No differences were noted in the growth zones or in the tendency to develop articular lesions in rats of the various groups. Possible differences in the amount of GAG in intervertebral discs of diabetic and non-diabetic rats respectively await further confirmation.These investigations were aided by grant No. 2 RO1 EYO 1837-03, of the Institute of Arthritis and Metabolic Disease, National Institutes of Health, Bethesda, Maryland, USA.We are indebted to Professor Dr J. Rüttner, Institute of Pathology, University of Zürich, for his permission to use the calculator.     

Vasotropic activity of arachidonic acid peroxide on the isolated murine portal vein and its modification by antiinflammatory substances

Zusammenfassung An der isolierten, autonom pulsierenden Portalvene der Maus zeigt Arachidonsäureperoxid einen ohne Tachyphylaxie-Erscheinungen wiederholbaren, vasotropen Effekt, der hauptsächlich in dosisabhängiger Steigerung der Kontraktionsfrequenz besteht. Dieser Effekt kann durch anti-inflammatorisch wirksame Substanzen entweder antagonistisch (Natriumsalicylat, Phenylbutazon, Aminopyrin) oder synergistisch (Tribenoside) beeinflusst werden. Die mit Arachidonsäureperoxid stimulierte Portalvene der Maus erscheint deshalb geeignet, Antiphlogistika zu differenzieren und Hinweise auf einen eventuellen Wirkungsmodus im Gebiet der terminalen Strombahn zu liefern.

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The technical assistance of Mr.A. Blättler is gratefully acknowledged.     

Growth,development, feeding preference,and food consumption and utilization by tobacco hornworm on tobacco mosaic virus-infected and non-infected tobacco leaves

Summary Plant disease may cause a variety of changes in plants which influence their suitability to insect herbivores. The reported physiological changes in tobacco due to infection by tobacco mosaic virus have the potential to influence the feeding, growth and behavior of the tobacco hornworm,Manduca sexta. However, feeding on foliage of systematically infected plants had no statistically significant effects on development time, mean pupal weight or the amount of foliage consumed by 4th instars. Although an initial preference was exhibited by larvae for healthy leaves after about 72 h no differences were observed. These results do not support the results of previous research on the influence of tobacco mosaic virus-infected plants on the tobacco hornworm.Scientific contribution No. 8130, article No. A-5071, of the Maryland Agricultural Experiment Station, Department of Entomology     

Action of insulin on the glycogen content of liver and muscle of the murrel,Ophicephalus striatus (Bloch)

Résumé Des doses variées d'insuline administrées à l'Ophicephalus striatus ont augmenté la quantité de glycogène du foie et des muscles. Dans le foie, les doses étant fortes (40 IU et 60 IU), la quantité normale de glycogène a presque quadruplé et elle a plus que septuplé dans les muscles. Le mécanisme possible présidant à l'action de l'insuline est aussi discuté.     

Cytosolic free Ca2+ in insulin secreting cells and its regulation by isolated organelles

The role of Ca2+ in secretagogue-induced insulin release is documented not only by the measurements of 45Ca fluxes in pancreatic islets, but also, by direct monitoring of cytosolic free Ca2+, [Ca2+]i. As demonstrated, using the fluorescent indicator quin 2, glyceraldehyde, carbamylcholine and alanine raise [Ca2+]i in the insulin secreting cell line RINm5F, whereas glucose has a similar effect in pancreatic islet cells. The regulation of cellular Ca2+ homeostasis by organelles from a rat insulinoma, was investigated with a Ca2+ selective electrode. The results suggest that both the endoplasmic reticulum and the mitochondria participate in this regulation, albeit at different Ca2+ concentrations. By contrast, the secretory granules do not appear to be involved in the short-term regulation of [Ca2+]i. Evidence is presented that inositol 1,4,5-trisphosphate, which is shown to mobilize Ca2+ from the endoplasmic reticulum, is acting as an intracellular mediator in the stimulation of insulin release.     

Cytosolic free Ca2+ in insulin secreting cells and its regulation by isolated organelles

Summary The role of Ca²⁺ in secretagogue-induced insulin release is documented not only by the measurements of⁴⁵Ca fluxes in pancreatic islets, but also, by direct monitoring of cytosolic free Ca²⁺, [Ca²⁺]_i. As demonstrated, using the fluorescent indicator quin 2, glyceraldehyde, carbamylcholine and alanine raise [Ca²⁺]_i in the insulin secreting cell line RINm5F, whereas glucose has a similar effect in pancreatic islet cells. The regulation of cellular Ca²⁺ homeostasis by organelles from a rat insulinoma, was investigated with a Ca²⁺ selective electrode. The results suggest that both the endoplasmic reticulum and the mitochondria participate in this regulation, albeit at different Ca²⁺ concentrations. By contrast, the secretory granules do not appear to be involved in the short-term regulation of [Ca²⁺]_i. Evidence is presented that inositol 1,4,5-trisphosphate, which is shown to mobilize Ca²⁺ from the endoplasmic reticulum, is acting as an intracellular mediator in the stimulation of insulin release.     

Protein arginine methylation: a prominent modification and its demethylation

Arginine methylation of histones is one mechanism of epigenetic regulation in eukaryotic cells. Methylarginines can also be found in non-histone proteins involved in various different processes in a cell. An enzyme family of nine protein arginine methyltransferases catalyses the addition of methyl groups on arginines of histone and non-histone proteins, resulting in either mono- or dimethylated-arginine residues. The reversibility of histone modifications is an essential feature of epigenetic regulation to respond to changes in environmental factors, signalling events, or metabolic alterations. Prominent histone modifications like lysine acetylation and lysine methylation are reversible. Enzyme family pairs have been identified, with each pair of lysine acetyltransferases/deacetylases and lysine methyltransferases/demethylases operating complementarily to generate or erase lysine modifications. Several analyses also indicate a reversible nature of arginine methylation, but the enzymes facilitating direct removal of methyl moieties from arginine residues in proteins have been discussed controversially. Differing reports have been seen for initially characterized putative candidates, like peptidyl arginine deiminase 4 or Jumonji-domain containing protein 6. Here, we review the most recent cellular, biochemical, and mass spectrometry work on arginine methylation and its reversible nature with a special focus on putative arginine demethylases, including the enzyme superfamily of Fe(II) and 2-oxoglutarate-dependent oxygenases.