Calcareous nannofossil age constraints on Miocene flysch sedimentation in the Outer Dinarides (Slovenia, Croatia, Bosnia-Herzegovina and Montenegro)

Flysch deposits are associated with the Outer Dinaride nappe front. They overlie Eocene platform carbonate to bathyal marl successions that subsequently cover Cretaceous platform carbonates of Apulia and the Dinaride nappes. Planktonic foraminifer biostratigraphy indicates Eocene age of flysch sedimentation. New calcareous nannofossil data reveal that several assemblages are present; besides the dominant Mid-Eocene species, Cretaceous, Paleocene, Oligocene and Miocene taxa were also identified throughout the entire flysch belt. Widespread occurrence of nannofossil species of zone NN4-6 indicates that flysch deposition lasted up to at least the Mid-Miocene. Ubiquitous occurrence of various pre-Miocene taxa demonstrates that extensive, possibly submarine, sediment recycling has occurred in the Cenozoic. As flysch remnants are typically sandwiched between thrust sheets, these new stratigraphic ages give a lower bracket on deformation age of the coastal range. The data provide a link between Cretaceous compression in the Bosnian Flysch and recent deformation in the Adriatic offshore area

The Lower Miocene volcaniclastic sedimentation in the Sicilian sector of the Maghrebian Flysch Basin: geodynamic implications

Abstract Volcaniclastic debris-rich formations, characterising the Troina–Tusa Unit in the Sicilian Maghrebian Chain, are examined. The Troina–Tusa Unit terrains sedimented in the Maghrebian Flysch Basin, which, from Jurassic to Early Miocene, constituted the southernmost branch of the Western Tethys, located between Africa and the Mesomediterranean Terrane margins. New field, biostratigraphic and petrographic data enable a reconstruction of the palaeogeographic and structural evolution of the Flysch Basin immediately before its deformation. All the studied formations transpired to be Burdigalian in age. The sandstone compositions, showing different source areas (magmatic arc, recycled orogen and continental block), indicate a provenance for the clastic material from a crystalline basement with an active volcanic arc, replaced by a remnant volcanic arc, which was rapidly completely eroded. The source area that has been considered is Sardinia, where Upper Oligocene–Aquitanian calc-alkaline volcanites are widespread, but the sedimentological characteristics and the Burdigalian age do not fit with this provenance. The Burdigalian calc-alkaline arc should be located on the internal side of the Troina–Tusa Basin, above the already stacked Peloritanian units. A migration of the volcanic activity, connected with the subduction plain roll-back, can be envisaged from the Sardinia Block to the Peloritanian Chain, this latter still docked to the Sardinia–Corsica massif

Costruire con la gente, una Casa Comunitaria nel villaggio di Santa Cruz Tepetotutla, Oaxaca, Messico

Viaggiare. Aprire gli occhi su realtà lontane e sconosciute, sorprendersi e mettere in discussione convinzioni radicate negli anni. Confrontarsi con la vita di chi lotta ogni giorno per affermare il diritto ad un’esistenza dignitosa. Mettersi alla prova. Lavorare, sporcarsi le mani e impregnarsi di sudore. Vedere giorno per giorno crescere un’idea che acquisisce concretezza, si trasforma in materia. Questo libro, il cui titolo riprende il famoso testo di Hassan Fathy, è il racconto di tutto questo: un viaggio di un gruppo di studenti e giovani architetti, attraverso la progettazione e la costruzione di una Casa Comunitaria, nel villaggio indigeno di Santa Cruz Tepetotutla, nello stato di Oaxaca, Messico. Il Progetto Messico è un progetto didattico di Cooperazione allo Sviluppo in Architettura nato sulla scia del Praktikumsseminar Mexiko, che la professoressa Ingrid Goetz porta avanti da 8 anni nella Technische Universität di Berlino. Di ritorno dall’esperienza berlinese di studio e di cantiere, e laureatasi da pochi mesi in Architettura a Napoli, Roberta Nicchia ha riunito un gruppo di studenti della sua Facoltà di provenienza intorno ad un caso studio concreto, la Casa Comunitaria. Questa è l’elemento propulsore di un progetto di percorso ecoturistico, che parte dal villaggio di Santa Cruz Tepetotutla e coinvolge varie comunità limitrofe. Esso si inserisce in un processo più ampio di “Planeación del Desarrollo Territorial Sustentable de la Chinantla Alta de Oaxaca”, un piano per lo sviluppo sostenibile del territorio, elaborato dagli abitanti della regione nel tentativo di generare forme alternative di reddito. L’Ecoturismo ha cominciato ad attecchire negli ultimi anni tra varie comunità indigene messicane, come risposta allo sfruttamento selvaggio del territorio che si va delineando nel Plan Puebla-Panamà. L’ottica è quella di promuovere la conservazione e valorizzazione del patrimonio naturale e dell’identità di luoghi ancora incontaminati e, allo stesso tempo, di far conoscere le condizioni di vita e la lotta delle popolazioni che difendono le loro terre dalla speculazione in atto. È dal sogno della comunità chinanteca di uscire dallo stato di emarginazione e povertà in cui versa, che ha origine l’Associazione Archintorno. Nell’affrontare questioni logistiche e di mediazione culturale, l’associazione si è avvalsa del prezioso aiuto dell’etnologa Angela Basoli, da anni residente in Messico per studiare da vicino la cultura chinanteca, e dell’ONG di Oaxaca “C.A.M.P.O. A.C.”, partner locale nel progetto, che lavora da oltre venti anni con le comunità della Chinantla Alta. Partendo, dunque, dal progetto di autosviluppo della comunità indigena, il Progetto Messico si pone obiettivi più ampi, affrontando una serie di tematiche legate alla progettazione nelle realtà marginali del Sud del Mondo e, più in generale, ad un diverso modo di fare Architettura. L’attenzione viene posta su temi innovativi e di impegno sociale, su un approccio concreto alle problematiche pratiche dell’esecuzione e su un metodo progettuale partecipativo, che ha coinvolto la comunità e la ONG locale nella elaborazione di un progetto condiviso. Il nostro viaggio parte da Napoli, con il laboratorio interdisciplinare “Progettazione Architettonica per il sud del mondo”, presso la Facoltà di Architettura nell’a.a. 2005/2006. Il corso si è proposto di fornire strumenti teorici e tecnici per l’acquisizione di una metodologia progettuale sensibile alle specificità ambientali, culturali ed economiche dei Paesi del Sud del mondo. Il tema della Casa Comunitaria è stato sviluppato dagli studenti prevedendo la rilettura della cultura dell’abitare, delle risorse e delle tecniche costruttive locali, più o meno tradizionali, nell’ambito di una visione “moderna” e sostenibile. Questo approccio progettuale rappresenta il contributo specifico che abbiamo ritenuto di poter offrire, in quanto giovani architetti, all’incontro interculturale con la comunità indigena messicana. Lo studio e la sperimentazione progettuale, oggetto del laboratorio, trovano pratica applicazione nella fase del cantiere didattico, svoltosi dal 30 novembre 2006 al 22 febbraio 2007, in cui, insieme alla popolazione locale, abbiamo costruito la Casa Comunitaria a Santa Cruz Tepetotutla

ADP-ribose polymers localized on Ctcf–Parp1–Dnmt1 complex prevent methylation of Ctcf target sites

PARylation [poly(ADP-ribosyl)ation] is involved in the maintenance of genomic methylation patterns through its control of Dnmt1 [DNA (cytosine-5)-methyltransferase 1] activity. Our previous findings indicated that Ctcf (CCCTC-binding factor) may be an important player in key events whereby PARylation controls the unmethylated status of some CpG-rich regions. Ctcf is able to activate Parp1 [poly(ADP-ribose) polymerase 1], which ADP-ribosylates itself and, in turn, inhibits DNA methylation via non-covalent interaction between its ADP-ribose polymers and Dnmt1. By such a mechanism, Ctcf may preserve the epigenetic pattern at promoters of important housekeeping genes. The results of the present study showed Dnmt1 as a new protein partner of Ctcf. Moreover, we show that Ctcf forms a complex with Dnmt1 and PARylated Parp1 at specific Ctcf target sequences and that PARylation is responsible for the maintenance of the unmethylated status of some Ctcf-bound CpGs. We suggest a mechanism by which Parp1, tethered and activated at specific DNA target sites by Ctcf, preserves their methylation-free status

Mouse Ribosomal RNA Genes Contain Multiple Differentially Regulated Variants

Previous cytogenetic studies suggest that various rDNA chromosomal loci are not equally active in different cell types. Consistent with this variability, rDNA polymorphism is well documented in human and mouse. However, attempts to identify molecularly rDNA variant types, which are regulated individually (i.e., independent of other rDNA variants) and tissue-specifically, have not been successful. We report here the molecular cloning and characterization of seven mouse rDNA variants (v-rDNA). The identification of these v-rDNAs was based on restriction fragment length polymorphisms (RFLPs), which are conserved among individuals and mouse strains. The total copy number of the identified variants is less than 100 and the copy number of each individual variant ranges from 4 to 15. Sequence analysis of the cloned v-rDNA identified variant-specific single nucleotide polymorphisms (SNPs) in the transcribed region. These SNPs were used to develop a set of variant-specific PCR assays, which permitted analysis of the v-rDNAs' expression profiles in various tissues. These profiles show that three v-rDNAs are expressed in all tissues (constitutively active), two are expressed in some tissues (selectively active), and two are not expressed (silent). These expression profiles were observed in six individuals from three mouse strains, suggesting the pattern is not randomly determined. Thus, the mouse rDNA array likely consists of genetically distinct variants, and some are regulated tissue-specifically. Our results provide the first molecular evidence for cell-type-specific regulation of a subset of rDNA

Parp1 Localizes within the Dnmt1 Promoter and Protects Its Unmethylated State by Its Enzymatic Activity

Aberrant hypermethylation of CpG islands in housekeeping gene promoters and widespread genome hypomethylation are typical events occurring in cancer cells. The molecular mechanisms behind these cancer-related changes in DNA methylation patterns are not well understood. Two questions are particularly important: (i) how are CpG islands protected from methylation in normal cells, and how is this protection compromised in cancer cells, and (ii) how does the genome-wide demethylation in cancer cells occur. The latter question is especially intriguing since so far no DNA demethylase enzyme has been found.Our data show that the absence of ADP-ribose polymers (PARs), caused by ectopic over-expression of poly(ADP-ribose) glycohydrolase (PARG) in L929 mouse fibroblast cells leads to aberrant methylation of the CpG island in the promoter of the Dnmt1 gene, which in turn shuts down its transcription. The transcriptional silencing of Dnmt1 may be responsible for the widespread passive hypomethylation of genomic DNA which we detect on the example of pericentromeric repeat sequences. Chromatin immunoprecipitation results show that in normal cells the Dnmt1 promoter is occupied by poly(ADP-ribosyl)ated Parp1, suggesting that PARylated Parp1 plays a role in protecting the promoter from methylation.In conclusion, the genome methylation pattern following PARG over-expression mirrors the pattern characteristic of cancer cells, supporting our idea that the right balance between Parp/Parg activities maintains the DNA methylation patterns in normal cells. The finding that in normal cells Parp1 and ADP-ribose polymers localize on the Dnmt1 promoter raises the possibility that PARylated Parp1 marks those sequences in the genome that must remain unmethylated and protects them from methylation, thus playing a role in the epigenetic regulation of gene expression

MeCP2 binds to nucleosome free (linker DNA) regions and to H3K9/H3K27 methylated nucleosomes in the brain

Methyl-CpG-binding protein 2 (MeCP2) is a chromatin-binding protein that mediates transcriptional regulation, and is highly abundant in brain. The nature of its binding to reconstituted templates has been well characterized in vitro. However, its interactions with native chromatin are less understood. Here we show that MeCP2 displays a distinct distribution within fractionated chromatin from various tissues and cell types. Artificially induced global changes in DNA methylation by 3-aminobenzamide or 5-aza-2′-deoxycytidine, do not significantly affect the distribution or amount of MeCP2 in HeLa S3 or 3T3 cells. Most MeCP2 in brain is chromatin-bound and localized within highly nuclease-accessible regions. We also show that, while in most tissues and cell lines, MeCP2 forms stable complexes with nucleosome, in brain, a fraction of it is loosely bound to chromatin, likely to nucleosome-depleted regions. Finally, we provide evidence for novel associations of MeCP2 with mononucleosomes containing histone H2A.X, H3K9me2 and H3K27me3 in different chromatin fractions from brain cortex and in vitro. We postulate that the functional compartmentalization and tissue-specific distribution of MeCP2 within different chromatin types may be directed by its association with nucleosomes containing specific histone variants, and post-translational modifications