Explicit nomenclature and classification in Pliny’s Natural History XXXII

Pliny’s Natural History has been traditionally considered as the unoriginal work of an uncritical compiler. This has also been held to be true of the “biological” books, especially when one compares them with the works of Aristotle, one of Pliny’s main authorities in this domain. Aristotle’s achievements would be remarkable, especially in the field of classification, of which the philosopher is traditionally celebrated as the scientific father. However, by carefully reading HN XXXII it is possible to find a certain “taxonomic” awareness—as, for instance, the need for a more accurate nomenclature in order to distinguish some aquatic animals beyond the proliferation of different vernacular terms—which is not to be found in the works of Aristotle. This, in a rather positivist way, may seem to anticipate Renaissance naturalists, but is in fact the consequence of both Pliny’s encyclopedic project and contingent ethnobiological, linguistic and social factors.     

Isoform specific phosphorylation of p53 by protein kinase CK1

The ability of three isoforms of protein kinase CK1 (α, γ₁, and δ) to phosphorylate the N-terminal region of p53 has been assessed using either recombinant p53 or a synthetic peptide reproducing its 1–28 sequence. Both substrates are readily phosphoylated by CK1δ and CK1α, but not by the γ isoform. Affinity of full size p53 for CK1 is 3 orders of magnitude higher than that of its N-terminal peptide (K _m 0.82 μM vs 1.51 mM). The preferred target is S20, whose phosphorylation critically relies on E17, while S6 is unaffected despite displaying the same consensus (E-x-x-S). Our data support the concept that non-primed phosphorylation of p53 by CK1 is an isoform-specific reaction preferentially affecting S20 by a mechanism which is grounded both on a local consensus and on a remote docking site mapped to the K²²¹RQK²²⁴ loop according to modeling and mutational analysis.     

The insulin-degrading enzyme is an allosteric modulator of the 20S proteasome and a potential competitor of the 19S

The interaction of insulin-degrading enzyme (IDE) with the main intracellular proteasome assemblies (i.e, 30S, 26S and 20S) was analyzed by enzymatic activity, mass spectrometry and native gel electrophoresis. IDE was mainly detected in association with assemblies with at least one free 20S end and biochemical investigations suggest that IDE competes with the 19S in vitro. IDE directly binds the 20S and affects its proteolytic activities in a bimodal fashion, very similar in human and yeast 20S, inhibiting at (IDE)?≤?30 nM and activating at (IDE)?≥?30 nM. Only an activating effect is observed in a yeast mutant locked in the “open” conformation (i.e., the α-3ΔN 20S), envisaging a possible role of IDE as modulator of the 20S “open”–”closed” allosteric equilibrium. Protein–protein docking in silico proposes that the interaction between IDE and the 20S could involve the C-term helix of the 20S α-3 subunit which regulates the gate opening of the 20S.     

Protein synthesis inhibition induced by dimethylnitrosamine and diethylnitrosamine on isolated rat hepatocytes

Summary Time- and dose-dependent protein synthesis inhibition takes place following exposure to high doses of dimethylnitrosamine (DMN) or diethylnitrosamine (DENA) in isolated rat hepatocytes. The ability of DENA to depress protein synthesis is 5-fold higher than that of DMN. Cells inhibited by 60 min exposure to DMN or DENA, and then incubated in a nitrosamine-free medium, regain their initial rate of protein synthesis. This recovery is faster and more complete for DENA-treated cells.     

The European dimension for the mouse genome mutagenesis program

The European Mouse Mutagenesis Consortium is the European initiative contributing to the international effort on functional annotation of the mouse genome. Its objectives are to establish and integrate mutagenesis platforms, gene expression resources, phenotyping units, storage and distribution centers and bioinformatics resources. The combined efforts will accelerate our understanding of gene function and of human health and disease.