Nuclear localization and signalling activity of phosphoinositidase C beta in Swiss 3T3 cells.

The hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdInsP2) is a widespread receptor-coupled signalling system at the plasma membrane of most eukaryotic cells. The existence of an entirely separate nuclear phosphoinositide signalling system is suggested from evidence that purified nuclei synthesize PtdInsP2 and phosphatidylinositol 4-phosphate (PtdInsP) in vitro and that a transient decrease in the mass of these lipids occurs when Swiss 3T3 cells are cultured in the presence of insulin-like growth factor-1 (IGF-1). These IGF-1-dependent changes in inositol lipids coincide with an increase in nuclear diacyglycerol and precede translocation to the nucleus and activation of protein kinase C (refs 5, 6). Circumstantial evidence that links these changes with mitosis comes from the isolation of a 3T3 clone that expresses the type-1 IGF receptor and binds IGF-1 peptide but does not respond mitogenically or show transient mass changes in nuclear inositol lipids. A key question is how IGF-1 initiates the rapid breakdown of PtdInsP and PtdInsP2 in the nucleus. Here we present evidence that nuclei of 3T3 cells contain the beta-isozyme of phosphoinositidase C, whereas the gamma-isozyme is confined to the cytoplasm and that IGF-1 treatment stimulates exclusively the activity of nuclear phosphoinositidase C.     

Mutations in KANSL1 cause the 17q21.31 microdeletion syndrome phenotype

The chromosome 17q21.31 deletion syndrome is a genomic disorder characterized by highly distinctive facial features, moderate-to-severe intellectual disability, hypotonia and friendly behavior. Here, we show that de novo loss-of-function mutations in KANSL1 (also called KIAA1267) cause a full del(17q21.31) phenotype in two unrelated individuals that lack deletion at 17q21.31. These findings indicate that 17q21.31 deletion syndrome is a monogenic disorder caused by haploinsufficiency of KANSL1.     

Investigations into the effects of ACTH on the half-life of mitochondrial proteins in the rat adrenal cortex

Summary ACTH elongates the half-life of the mitochondrial proteins from the rat adrenal cortex, and chloramphenicol inhibits this effect of ACTH. The hypothesis is advanced that the ACTH-provoked stabilization of the adrenocortical mitochondrial proteins requires continuous mitochondrial DNA-dependent protein synthesis.     

Effects of chronic treatment with ACTH on the intracellular levels of cyclic-AMP and cyclic-GMP in the rat adrenal cortex.

The effects of chronic ACTH treatment on the increase in the intracellular concentration of cyclic-AMP and cyclic-GMP acutely elicited by ACTH in the rat adrenal cortex were investigated. The results are consistent with the hypothesis that chronic ACTH treatment stimulates a) the de novo synthesis of adenylate- and guanylate-cyclase or b) the synthesis of new specific membrane receptors for ACTH.     

Difference in resistance of subunits A and B ofVibrio cholerae toxin (choleragen) to treatment with pronase

Summary Disc electrophoresis in sodium dodecyl sulphate, performed on choleragen after incubation with pronase, only showed the band corresponding to the B subunit, while the A subunit was lost. When examined in immunodiffusion, the digested choleragen was still able to precipitate with specific antibodies. On the other hand, toxicity was considerably reduced.     

Shell mineralogy of Monodonta (Osilinus) articulata Lamark 1822

Summary The species Monodonta (Osilinus) articulata Lamark 1822 is recorded as having a shell with mixed minerals: a calcitic microstructural unit is comprised between 2 aragonitic layers.We thank Proff. G. Buccheri and A. Greco for identifying our specimens.     

Effect of heat-labile enterotoxin (LT) produced byEscherichia coli on in vitro cell proliferation

Summary Filtrates fromE. coli H10407 cultures, giving a positive response for heat-labile enterotoxin (LT) in the Y-1 cell test, show an inhibitory activity both on³H-thymidine uptake by Ehrlich ascites cells and on granulocytic-macrophagic precursors (CFU-C) in murine bone marrow.Acknowledgments. We gratefully acknowledge the expert technical assistance of L. Basso and A. Gerosa of Department of Pathology, Hospital of Desio.