Origin of the coelomic cavities and the heart in the polypterids (Pisces)]

In polypterus the mesodermal cavities appear quite late during embryonic life. They are generally small and they only get somewhat more voluminous in the anterior mesomeres (where they establish the pronephrie chambers) and in the ventral anterior mesoderm (where they become an embryonic pericardial cavity). The anlage of the heart appears in the anterior part of the tissue that is situated between the paired mesodermal cavities of these stages. It assumes some unawaited dispositions that are truly confusing in the case of a superficial inspection. It is only during larval life that a coelomic cavity appears all along the truncal part of the mesoderm. In the beginning this is a pericardio-peritoneal cavity. But because of the coalescence between several membranes an anterior cavity gets isolated and this one is the pericardial cavity of the adult specimens; this cavity is much more limited than its homonymic counterpart of the embryonic stages.     

Agarose slab-gel electrophoresis equipment.

Simple slab-gel molds which utilize the electrophoresis apparatus described by F. W. Studier (J. Mol. Biol.79, 237 (1973)) have been designed for pouring and running agarose slab-gels. Analytical gels in which many samples are run simultaneously facilitate the assay of many enzymes which lead to physical changes in DNA, whereas the preparative gels allow the separation of large quantities (1–20 mg) of DNA fragments.     

Inhibition of adenylate cyclase by transglutaminase-catalyzed reactions in pigeon erythrocyte ghosts

We report the occurrence in pigeon erythrocytes of a soluble Ca2+-dependent transglutaminase (TGase) activity. The effect of the erythrocyte ghost protein modifications, determined by TGase-catalyzed reactions, on adenylate cyclase, phospholipid methyltransferase I and II activities and on the lipidic matrix fluidity of the membrane was investigated by using a purified guinea pig liver TGase preparation. The results showed a significant inhibitory effect of such modifications both on the basal and on the variously stimulated (by NaF, Gpp(NH)p alone or in the presence of 1-isoproterenol) adenylate cyclase activity. By contrast, both the phospholipid methylation and the fluidity of the lipidic matrix of the membrane were unaffected by TGase-mediated reactions. These data suggest a new possible inhibitory mechanism of the cyclic AMP synthesis which might be triggered by the enhancement of the cytosolic Ca2+ concentration.     

Direct assay for phosphotransacetylase and acetyl-coenzyme A carboxylase by high-performance liquid chromatography

A simple and specific assay to measure the activity of two coenzyme A derivative-processing enzymes, i.e., phosphotransacetylase (EC 2.3.1.8) and acetyl-coenzyme A carboxylase (EC 6.4.1.2), is described. The assay is based on the HPLC analysis of the short-chain coenzyme A derivatives formed by the enzymatic reaction, viz., acetyl-CoA and malonyl-CoA. For this purpose, ion-pair reversed-phase HPLC conditions are optimized. Furthermore, the influence of several variables on the enzyme reaction is studied in order to get maximum activity. Due to its short analysis time, good selectivity, and chromatogram information, HPLC proves to be an excellent method for the assay of these enzymes.     

Phylogenetic study of transcortin using monoclonal antibodies

We produced monoclonal antibodies that recognise three distinct epitopes of human transcortin. These epitopes are present on transcortin of humans with normal and altered transcortin levels, as well as on a variant with lower affinity for cortisol. One epitope is present on transcortin of Old World Monkeys and apes, the others are only present on transcortin of apes. The epitopes are not present on transcortin of other species. These results indicate that human transcortin contains a highly evolved and a more conserved part.