Loss of Arc renders the visual cortex impervious to the effects of sensory experience or deprivation

A myriad of mechanisms have been suggested to account for the full richness of visual cortical plasticity. We found that visual cortex lacking Arc is impervious to the effects of deprivation or experience. Using intrinsic signal imaging and chronic visually evoked potential recordings, we found that Arc−/− mice did not exhibit depression of deprived-eye responses or a shift in ocular dominance after brief monocular deprivation. Extended deprivation also failed to elicit a shift in ocular dominance or open-eye potentiation. Moreover, Arc−/− mice lacked stimulus-selective response potentiation. Although Arc−/− mice exhibited normal visual acuity, baseline ocular dominance was abnormal and resembled that observed after dark-rearing. These data suggest that Arc is required for the experience-dependent processes that normally establish and modify synaptic connections in visual cortex.Howard Hughes Medical InstituteNational Science Foundation (U.S.

Antioxidant activity of extracts from calf thymus and wheat sprouts. Potential relation with their activity in aging reversibility.

The potential presence in animal and vegetal tissues of compounds able to reactivate some metabolic pathways slowed down in aging fascinated, in the last century, many researchers. Old rats treated with calf thymus extract re capable of recovering altered glycogen and lipid levels, RNA/DNA ratio and transcriptional activity of DNA dependent-RNA polymerase in rat liver. More recently aging reversibility has been obtained with extracts from wheat sprouts. Old mice treated with wheat sprouts extract showed a recovery of decreased DNA synthesis in hepatocytes primary cultures when compared with the old untreated ones. Moreover old dogs orally treated for a month with wheat sprouts powder showed a 25-40% reduction of lens opacity. At the same time it was reported that wheat sprout contain a strong cocktail of antioxidant compounds. The association of this results is interesting because the oxidative stress has been soundly referred to several pathologies and to aging. Accordingly, in the last two decades, an increasing interest has been focused on the study of natural products with antioxidant activity. Antioxidants may contribute to prevent cancer and delay aging. In this context we compared the antioxidant activities of extracts from calf thymus and wheat sprouts. This to evaluate how much it is plausible that the previously observed effects on the aging reversibility could be due to the action of antioxidant compounds. The results reported in this paper demonstrated that extracts from wheat sprout and calf thymus show very similar strong activity both in ferrocianide reduction and on superoxide radical scavenging. Calf thymus extract shows a remarkable presence of taurine and glutathione. However it is surprising that this extract contain also a significant level of polyphenol molecules. The level of taurine and compounds containing thiol groups are in wheat sprout extract much lower respect to calf thymus extract. On the contrary a remarkable content of reducing glycosides and flavonoids was observed. The very similar antioxidant activity demonstrated in this paper strongly support the exciting hypothesis that the cocktails of antioxidant molecules, contained in calf thymus and wheat sprouts, are responsible for the previously reported aging reversibility effects

Interaction of DDSDEEN peptide with N-CAM protein. Possible mechanism enhancing neuronal differentiation.

Interaction of DDSDEEN peptide with N-CAM protein. Possible mechanism enhancing neuronal differentiation Valeria Marsili a,b,*, Giulio Lupidi c, Giuliano Berellini d, Isabella Calzuola a,b, Stefano Perni a,b, Gabriele Cruciani d, Gian Luigi Gianfranceschi a,b a Dipartimento di Biologia Cellulare e Ambientale, Universita` di Perugia, 06123 Perugia, Italy b CEMIN (Centro Eccellenza Materiali Innovativi Nanostrutturati), 06123 Perugia, Italy c Dipartimento di Biologia MCA, Universita` di Camerino, 62032 Camerino, Italy d Dipartimento di Chimica, Universita` di Perugia, 06123 Perugia, Italy ab s t r a c t DDSDEEN chromatin peptide, after dansylation, was studied for its ability to bind N-CAM protein. The binding causes a quenching of the Dns-peptide fluorescence emission. Doseand time-dependent binding of Dns-peptide with N-CAM has been shown. Fluorescence quenching is completely lost if the Dns-peptide is subjected to carboxypeptidase digestion. Moreover the undansylated peptide pEDDSDEEN competes with the DnsDDSDEEN peptide for the binding with the N-CAM protein. The Dns-peptide–N-CAM bond has been related to the peptide biological activity probably involved in the promotion of neuronal differentiation. An attempt to recognize a possible N-CAM binding site for Dns-peptide was performed by alignment of N-CAM from various sources with some sequences that have been previously reported as binding sites for the pEDDSDEEN and DDSDEEN peptides. Interestingly, the alignment of N-CAM from various sources with the peptides WHPREGWAL and WFPRWAGQA recognizes on rat and human N-CAM a unique sequence that could be the specific binding site for chromatin peptide: WHSKWYDAK. This sequence is present in fibronectin type-III domain of N-CAM. In addition molecular modeling studies indicate the N-CAM sequence WHSKWYDAK as, probably, the main active site for DnsDDSDEEN (or pEDDSDEEN) peptide ligand. Accordingly the binding experiments show a high affinity between WHSKWYDAK and DnsDDSDEEN peptides

Phosphorylation of synthetic acidic peptides by casein kinase II: evidence for competition with phosphorylation of proteins involved in transcription.

Phosphorylation of several synthetic acidic peptides by biochemically isolated casein kinase II (CKII) and by cellular and nuclear extracts containing CKII-like activity has been investigated. Especially the synthetic peptide pyroGlu-Asp-Asp-Ser-Asp-Glu-Glu-Asn comprising the carboxy-terminal acidic hepta-peptide of the largest subunit of RNA polymerase II was found to serve as an excellent substrate for purified CKII. Moreover, this peptide reduces the rate of 'in vitro' ATP-dependent stimulation of DNA transcription induced by the proteins in the extracts. Since the peptide itself is also significantly phosphorylated in such assays, it is supposed that it serves as a competitive substrate for the phosphorylation of proteins in the extracts whose phosphorylation seems to be a prerequisite for their activity in the transcription process. This points to the involvement of CKII and substrate(s) of CKII in the process of transcription