Fossilized bacteria in a Cretaceous pterosaur headcrest

Pinheiro F.L., Horn B.L.D., Schultz C.L., de Andrade J.A.F.G. and Sucerquia P.A., 2012: Fossilized bacteria in a Cretaceous pterosaur headcrest. Lethaia, Vol. 45, pp. 495-499. We report herein the first evidence of bacterial autolithification in the Crato Formation of Araripe Basin, Brazil. The fossilized bacteria are associated with a tapejarid pterosaur skull, replacing the soft-tissue extension of the headcrest. EDS analyses indicate that the bacteria were replaced by phosphate minerals, probably apatite. The bacterial biofilm was likely part of the prokaryotic mat that decomposed the pterosaur carcass at the bottom of the Araripe lagoon. This work suggests that bacterial autolithification could have played a key-role on soft-tissue preservation of Crato Formation Lagerstatte. ?Bacterial autolithification, Crato Formation, phosphatization, pterosaur, soft-tissue preservation.

Stratigraphy and Palaeontology of the Late Cretaceous Wapiti Formation, west-central Alberta, Canada

A complete stratigraphic assessment and revision of the middle Campanian to upper Maastrichtian Wapiti Formation in north-western Alberta and north-eastern British Columbia is the main aim of this research project. The study area encompasses an area of approximately 200X180 km in the Grande Prairie County (west-central Alberta) and easternmost British Columbia, Canada. Results presented here indicate that the 1300m thick succession currently reported in the literature as “undifferentiated lithostratigraphic unit”, consists of five lithostratigraphic units and four unconformity-bounded depositional sequences; their study and description have been documented integrating several geological disciplines, including sequence stratigraphic methods, well-log signatures, facies analysis, and fossil associations. On the whole, particular attention has been given to 1) age and nature of both basal and upper contacts of the Wapiti Formation, 2) effective mappability of lithostratigraphic units and depositional sequences in western Alberta, and 3) the identification of previously undetermined maximum flooding surface of the Bearpaw seaway and Drumheller Marine Tongue, which are reference marine unit in central and southern Alberta. A second, but not less important, guideline for the project has been the rich paleontological record of the Wapiti deposits. Detailed paleoenvironmental and taxonomical information on old and new finds have been the base for correlation with well known associations of Alaska, southern Alberta, and Montana. Newly discovered rich fossil localities documented an extraordinarily diverse fauna during the latest Cretaceous, including dinosaurs, squamates, and fresh-water fishes and reptiles. Lastly, in order to better characterize the Wapiti Formation, major marker beds were described: these include several bentonites (altered volcanic ash deposits) which have been documented over an area of almost 30.000 km2, as well as four major coal zones, characterized by tabular coal seams with an overall thickness of 2 meters. Such marker beds represent a formidable tool for high-resolution chronology and regional correlations within the Late Cretaceous Alberta foreland basin.

Paleontological studies of Cretaceous vertebrate fossil beds in the Tataouine Basin (southern Tunisia)

The ‘Continental Intercalaire’ deposits of the Tataouine basin of southern Tunisia preserve one of the most diverse Cretaceous vertebrate fauna from Africa. This research project focuses on a detailed revision of the stratigraphic distribution of mid-Cretaceous fossil beds in the Tataouine Basin and includes the description of four, newly discovered vertebrate tracksites. In the Tataouine region, macro- and microvertebrate remains are recovered from three stratigraphic intervals: the lower Douiret Formation (Barremian), the Chenini (rare) and Oum ed Diab members of the A��n El Guettar Formation (Albian). A detailed, basin-scale revision of the stratigraphic occurrence of fossil-bearing strata indicates 1. lateral facies variability within the context of a low gradient, circalittoral to coastal-plain environment; 2. multiple and diachronous fossil beds which include elasmobranchs, actinopterygians, sarcopterygians, turtles, crocodyliforms, pterosaurs, and non-avian dinosaurs remains. Four vertebrate tracksites have been discovered in the study area: 1. the Middle Jurassic Beni Ghedir site which preserves approximately 130 tridactyl footprints distributed over an area of 200 square meters, representing the oldest evidence of a dinosaur fauna in Tunisia; 2. the late Albian Chenini tracksite, which includes poorly preserved crocodilian tracks and the dinosaur ichnospecies Apulosauripus federicianus; 3. the Cenomanian Ksar Ayaat locality, where footprints assigned to a pleurodiran turtle are exposed, and 4. the upper Cenomanian Jebel Boulouha site which presents almost 100 well-preserved tridactyl tracks referred to small-sized theropods, fossil bird tracks - ichnogenus Koreanaorins – and tracks referred to a mammalian trackmaker, representing the first report of fossil bird and mammal from the Cretaceous of continental Africa and Tunisia respectively. In addition, data collected from the Tunisian tracksites have been compared with coeval tracksites in Italy and Croatia, showing analogies in morphology and paleoenvironment of dinosaur ichnoassociations, supporting the already hypothesized subaerial connection between these areas during the mid-Cretaceous.

Modelling growth dynamics and toxin production in Ostreopsis cf. ovata

The benthic dinoflagellate O. ovata represents a serious threat for human health and for the ecology of its blooming areas: thanks to its toxicity this microalga has been responsible for several cases of human intoxication and mass mortalities of benthic invertebrates. Although the large number of studies on this dinoflagellate, the mechanisms underpinning O. ovata growth and toxin production are still far to be fully understood. In this work we have enriched the dataset on this species by carrying out a new experiment on an Adriatic O. cf. ovata strain. Data from this experiment (named Beta) and from another comparable experiment previously conducted on the same strain (named Alpha), revealed some interesting aspects of this dinoflagellate: it is able to grow also in a condition of strong intracellular nutrient deficiency (C:P molar ratio > 400; C:N > 25), reaching extremely low values of chlorophyll-a to carbon ratio (0.0004). Was also found a significant inverse relationships (r > -0.7) between cellular toxin to carbon and cellular nutrient to carbon ratios of experiment Alpha. In the light of these result, we hypothesized that in O. cf. ovata nutrient-stress conditions (intended as intracellular nutrient deficiency) can cause: i) an increase in toxin production; ii) a strong decrease in chlorophyll-a synthesis; iii) a lowering of metabolism associated with the formation of a sort of resting stage. We then used a modelling approach to test and critically evaluate these hypotheses in a mechanistic way: newly developed formulation describing toxin production and fate, and ad hoc changes in the already existent formulations describing chlorophyll synthesis, rest respiration, and mortality, have been incorporated in a simplified version of the European Regional Seas Ecosystem Model (ERSEM), together with a new ad hoc parameterization. The adapted model was able to accurately reproduce many of the trends observed in the Alpha experiment, allowing us to support our hypotheses. Instead the simulations of the experiment Beta were not fully satisfying in quantitative terms. We explained this gap with the presumed different physiological behaviors between the algae of the two experiments, due to the different pre-experimental periods of acclimation: the model was not able to reproduce acclimation processes in its simulations of the experiment Beta. Thus we attempt to simulate the acclimation of the algae to nutrient-stress conditions by manual intervention on some parameters of nutrient-stress thresholds, but we received conflicting results. Further studies are required to shed light on this interesting aspect. In this work we also improve the range of applicability of a state of the art marine biogeochemical model (ERSEM) by implementing in it an ecological relevant process such as the production of toxic compounds.

Struttura filogenetica della comunità batterica associata ad Ostreopsis cf. Ovata in colture batch e dinamiche di crescita

Negli ultimi 10 anni i blooms attribuibili alla dinoflagellata bentonica Ostreopsis cf. ovata sono aumentati in termini di frequenza ed intensità lungo le coste del Mediterraneo, avendo ripercussioni negative sulla salute umana e forti impatti sulle comunità marine bentoniche, ciò a seguito della produzione di potenti tossine (composti palitossina-simili) da parte della microalga. Tra i fattori ecologici che innescano o regolano le dinamiche dei bloom tossici le interazioni tra microalghe e batteri sono in misura sempre maggiore oggetto di ricerca. In questo studio è stata analizzata la struttura filogenetica della comunità batterica associata ad O. cf. ovata in colture batch e valutate le dinamiche successionali della stessa in relazione alle differenti fasi di crescita della microalga (oltre che in relazione alle dinamiche di abbondanza virale). Lo studio filogenetico è stato effettuato tramite l’ausilio di metodiche molecolari di sequenziamento di next generation (Ion Torrent). Le abbondanze dei batteri e delle particelle virali sono state determinate tramite microscopia ad epifluorescenza; l’abbondanza cellulare algale è stata stimata tramite metodo Uthermohl. Il contributo della frazione batterica ad elevata attività respiratoria è stato determinato tramite doppia colorazione con coloranti DAPI e CTC. Dai dati emersi si evince che la comunità batterica attraversa due fasi di crescita distinte, una più marcata e concomitante con la fase esponenziale di O. cf. ovata, l'altra quando la microalga è in fase media stazionaria. Per quanto concerne la composizione filogenetica della comunità sono stati rilevati 12 phyla, 17 classi e 150 generi, sebbene i dati ottenuti abbiano rilevato una forte dominanza del phylum Proteobacteria con la classe Alphaproteobacteria, seguita dal phylum Bacteroidetes con la classe Sphingobacteria. Variazioni nella struttura filogenetica della comunità batterica, a livello di generi, tra le diverse fasi di crescita della microalga ha permesso di evidenziare ed ipotizzare particolari interazioni di tipo mutualistico e di tipo competitivo.

Dinamiche di produzione di Dimetilsolfoniopropionato (DMSP) nella dinoflagellata tossica Ostreopsis cf. ovata in colture batch

Il Dimetilsolfoniopropionato (DMSP) è un metabolita secondario prodotto da vari organismi marini, tra cui molte microalghe. Ad oggi pochi studi riguardano gli effetti dei fattori ambientali sulla produzione di DMSP nelle microalghe tossiche, tuttavia si ipotizza che la carenza di azoto (N-dep) possa influire sulla produzione di tossine e DMSP. In questo lavoro è stata indagata nella dinoflagellata Ostreopsis cf. ovata: la presenza e l’andamento del DMSP lungo tutte le fasi di crescita; i possibili effetti di differenti condizioni di crescita (i.e. bilanciata e N-dep) sulla produzione del metabolita e delle tossine. La scelta della dinoflagellata è giustificata dalle sue frequenti fioriture dannose nel Mediterraneo e dall’osservazione, in studi pregressi, di una comunità batterica associata ai suoi blooms in grado di utilizzare il DMSP come fonte energetica. Lo studio mostra per la prima volta da parte di O. cf ovata la produzione del DMSP, riportando un trend temporale simile nelle due condizioni. Si evidenzia: un minimo a fine fase esponenziale; un massimo nella prima fase stazionaria; una riduzione al termine della fase stazionaria. Il confronto fra le due condizioni evidenzia un effetto positivo di N-dep nella produzione di DMSP, evidenziato anche dal maggior tasso di produzione, che potrebbe avvenire per: utilizzare il DMSP rispetto ad altri osmoliti azotati; rilasciare nell’ambiente composti carboniosi e sulfurei, prodotti a seguito dello stress cellulare. I risultati indicherebbero come N-dep possa interferire nella sintesi di tossine e DMSP in maniera opposta, non per competizione diretta del nutriente nei processi di sintesi, ma a seguito dei cambiamenti fisiologici della microalga dovuti alla carenza nutrizionale. Infine la produzione di DMSP da parte della microalga conferma l’instaurarsi di una fase d’interazione mutualistica con i batteri ad essa associati facilitata dal DMSP, importante per lo sviluppo della popolazione algale e dei conseguenti rischi sanitari ed ecosistemici.

Characterization of vascular cavity coatings and microscopic tube-shaped structures from Upper Cretaceous dinosaur bone: evidence of a bacterial origin for dinosaur blood vessels""

Recent claims of blood vessels extracted from dinosaur fossils challenge classical views of soft-tissue preservation. Alternatively, these structures may represent postdepositional,diagenetic biofilms that grew on vascular cavity surfaces within the fossil. Similar red, hollow, tube-shaped structures were recovered from well-preserved and poorly-preserved (abraded, desiccated, exposed) Upper Cretaceous dinosaur fossils in this study. Integration of light microscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy was used to compare these vessel structures to the fossils from which they are derived. Vessel structures are typically 100-400 μm long, 0.5-1.5 μm thick, 10-40 μm in diameter and take on a wide range of straight, curved, andbranching morphologies. Interior surfaces vary from smooth to globular and typically contain spheres, rods, and fibrous structures (< 2 μm in diameter) incorporated into the surface. Exterior surfaces exhibit 2-μm-tall converging ridges, spaced 1-3 μm apart, that are sub-parallel to the long axis of the vessel structure. Fossil vascular cavities are typically coated with a smooth or grainy orange layer that shows a wide range of textures including smooth, globular, rough, ropy, and combinations thereof. Coatings tend to overlay secondary mineral crystals and framboids, confirming they are not primary structures of the fossil. For some cavity coatings, the surface that had been in contact with the bone exhibits a ridged texture, similar to that of vessel structures, having formed as a mold of the intravascular bone surface. Thus, vessel structures are interpreted as intact cavity coatings isolated after the fossil is demineralized. The presence of framboids and structures consistent in size and shape with bacteria cells, the abundance of iron in cavity coatings, and the growth of biofilms directly from the fossil that resemble respective cavity coatings support the hypothesis that vessel structures result from ironconsuming bacteria that form biofilms on the intravascular bone surfaces of fossil dinosaur bone. This also accounts for microstructures resembling osteocytes as some fossil lacunae are filled with the same iron oxide that comprises vessel structures andcoatings. Results of this study show that systematic, high-resolution SEM analyses of vertebrate fossils can provide improved insight on microtaphonomic processes, including the role of bacteria in diagenesis. These results conflict with earlier claims of dinosaurblood vessels and osteocytes.

Clinical and molecular characterization of the potential CF disease modifier syntaxin 1A

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator gene (CFTR). Disease severity in CF varies greatly, and sibling studies strongly indicate that genes other than CFTR modify disease outcome. Syntaxin 1A (STX1A) has been reported as a negative regulator of CFTR and other ion channels. We hypothesized that STX1A variants act as a CF modifier by influencing the remaining function of mutated CFTR. We identified STX1A variants by genomic resequencing patients from the Bernese CF Patient Data Registry and applied linear mixed model analysis to establish genotype-phenotype correlations, revealing STX1A rs4363087 (c.467-38A>G) to significantly influence lung function. The same STX1A risk allele was recognized in the European CF Twin and Sibling Study (P=0.0027), demonstrating that the genotype-phenotype association of STX1A to CF disease severity is robust enough to allow replication in two independent CF populations. rs4363087 is in linkage disequilibrium to the exonic variant rs2228607 (c.204C>T). Considering that neither rs4363087 nor rs2228607 changes the amino-acid sequence of STX1A, we investigated their effects on mRNA level. We show that rs2228607 reinforces aberrant splicing of STX1A mRNA, leading to nonsense-mediated mRNA decay. In conclusion, we demonstrate the clinical relevance of STX1A variants in CF, and evidence the functional relevance of STX1A variant rs2228607 at molecular level. Our findings show that genes interacting with CFTR can modify CF disease progression.European Journal of Human Genetics advance online publication, 10 April 2013; doi:10.1038/ejhg.2013.57.

Large deletions in the CFTR gene: clinics and genetics in Swiss patients with CF

Cystic fibrosis (CF) is the most common life-shortening autosomal recessive disorder in Caucasians, and is associated with at least one mutation on each CF transmembrane conductance regulator (CFTR) allele. Some patients, however, with only one identifiable point mutation carry on the other allele, a large deletion that is not detected by conventional screening methods. The overall frequency of large deletions in patients with CF is estimated to be 1-3%. Using the CFTR Multiplex Ligation dependent Probe Amplification Kit (MRC-Holland, Amsterdam, Netherlands) that allows the exact detection of copy numbers from all 27 exons in the CFTR gene, we screened 50 patients with only one identified mutation for large deletions in the CFTR gene. Each detected deletion was confirmed using our real-time polymerase chain reaction (PCR) assay and deletion-specific PCR reactions using junction fragment primers. We detected large deletions in eight patients (16%). These eight CF alleles belong to four different deletion types (CFTRindel2, CFTRdele14b-17b, CFTRdele17a-17b and CFTRdele 2-9) whereof the last is novel. Comparing detailed clinical data of all these patients with CF and the molecular genetic findings, we were able to elaborate criteria for deletion screenings and possible genotype-phenotype associations. In conclusion, we agree with other authors that deletion screenings should be implemented in routine genetic diagnostics of CF.