Fossil lizards and snakes from Ano Metochi – a diverse squamate fauna from the latest Miocene of northern Greece

We here describe a new squamate fauna from the late Miocene (Messinian, MN 13) of Ano Metochi, northern Greece. The lizard fauna of Ano Metochi is here shown to be rather diverse, consisting of lacertids, anguids, and potential cordylids, while snakes are also abundant, consisting of scolecophidians, natricines and at least two different colubrines. If our identification is correct, the Ano Metochi cordylids are the first ones identified from Greece and they are also the youngest representatives of this group in Europe. A previously described scincoid from the adjacent locality of Maramena is here tentatively also referred to cordylids, strengthening a long term survival of this group until at least the latest Miocene. The scolecophidian from Ano Metochi cannot be attributed with certainty to either typhlopids or leptotyphlopids, which still inhabit the Mediterranean region. The find nevertheless adds further to the poor fossil record of these snakes. Comparison of the Ano Metochi herpetofauna with that of the adjacent locality of Maramena reveals similarities, but also striking differences among their squamate compositions

Osteology, fossil record and palaeodiversity of the European lizards

he capability of palaeontologists to identify fossil remains of a particular group of vertebrates strongly depends on the knowledge they have of its comparative osteology and on the actual presence of diagnostic differences among the considered taxa. This could have a relevant influence on the study of palaeodiversity, since a low recognisability causes a loss of data when trying to reconstruct the history of taxa that lived on Earth in the past. Currently, more than 6000 extant species of lizards and worm lizards are known, and new ones continue to be discovered, mainly based on molecular data. But are we able to recognise this high diversity using osteology? As far as European taxa are concerned, the osteological recognisability of non-snake squamates is very low: only 31% of the extant European taxa can be identified based on their skeletal morphology. This is balanced partially by the fact that most recognisable taxa have been actually recognised in the fossil record, suggesting that the lost data are mainly due to the scarce knowledge of the comparative osteology of these reptiles and less influenced by other biases, such as taphonomic or collection biases. In this context, specimen-level phylogenetic analysis has proved to be a useful tool to identify diagnostic combinations of osteological features, at least for lacertid species, as evidenced by a case study focused on the genus Lacerta

A review of the fossil record of old world turtles of the clade pan-trionychidae

Turtles of the clade Pan-Trionychidae have a rich fossil record in the Old World, ranging from the Early Cretaceous (Hauterivian) to the Holocene. The clade most probably originated in Asia during the Early Cretaceous but spread from there to the Americas and Europe by the Late Cretaceous, to India and Australia by the Eocene, and to Afro-Arabia by the Neogene. The presence of a single pan-cyclanorbine in the Late Cretaceous (Maastrichtian) of Asia provides a minimum estimate for the age of the trionychid crown. As preserved, diversity was relatively high in Asia during the Late Cretaceous, but the subsequent, strong decline is likely a preservational bias, as extant faunas are relatively rich, especially throughout Asia. The range of trionychids contracted southward in Europe over the course of the Neogene, and the group is now locally extirpated. The group is now similarly absent from Arabia and Australia. A taxonomic review of the 180 named Old World taxa finds 42 nomina valida, 38 nomina invalida, 88 nomina dubia, 11 nomina nuda, and 1 nomen suppressum

Lizards and snakes from the late Miocene hominoid locality of Ravin de la Pluie (Axios Valley, Greece)

We here describe lizards and snakes from the late Miocene (MN 10) of Ravin de la Pluie, near Thessaloniki, Greece, a locality widely known for its hominoid primate Ouranopithecus macedoniensis. The new finds comprise two large-sized lizards (a probable anguine and a varanid) and two snakes (an elapid and a small-sized “colubrine”). Even if the material is represented by few specimens, this is the first record of squamates from the late Miocene MN 10 biozone of southeastern Europe and the third only for the whole continent. The importance of the varanid vertebrae for systematic attributions is discussed. The new varanid limb elements described herein rank among the few such specimens in the fossil record of monitor lizards. Judging from the new and previously published varanid appendicular material, we suggest that Neogene monitor lizards from Europe possessed comparatively short and robustly built limbs. Distinctive scars on one of the limb elements are interpreted as bite marks of a predator or scavenger, offering insights on the palaeoecology of the herpetofauna of the locality

Differential hydrophobicity drives self-assembly in Huntington's disease

Identifying the driving forces and the mechanism of association of huntingtin-exon1, a close marker for the progress of Huntington's disease, is an important prerequisite towards finding potential drug targets, and ultimately a cure. We introduce here a modelling framework based on a key analogy of the physico-chemical properties of the exon1 fragment to block copolymers. We use a systematic mesoscale methodology, based on Dissipative Particle Dynamics, which is capable of overcoming kinetic barriers, thus capturing the dynamics of significantly larger systems over longer times than considered before. Our results reveal that the relative hydrophobicity of the poly-glutamine block as compared to the rest of the (proline-based) exon1 fragment, ignored to date, constitutes a major factor in the initiation of the self-assembly process. We find that the assembly is governed by both the concentration of exon1 and the length of the poly-glutamine stretch, with a low length threshold for association even at the lowest volume fractions we considered. Moreover, this self-association occurs irrespective of whether the glutamine stretch is in random coil or hairpin configuration, leading to spherical or cylindrical assemblies, respectively. We discuss the implications of these results for reinterpretation of existing research within this context, including that the routes towards aggregation of exon1 may be distinct to those of the widely studied homopolymeric poly-glutamine peptides

First record of fossil anguines (Squamata; Anguidae) from the Oligocene and Miocene of Turkey

Fossil anguine lizard specimens from several Turkish localities are described in this paper. The material comes from ten different localities, spanning a large geographic area consisting of both parts of the European Turkey and Anatolia, and ranging in age from the Oligocene to the Late Miocene. In certain cases, the generic determination was possible and, accordingly, members of Ophisaurus and Anguis were identified and described in detail. The specimens of Anguis, found in different, Middle and Late Miocene localities from Anatolia, represent two of only a few fossil occurrences of this taxon. Moreover, the material reported herein represents the oldest occurrences of anguine lizards, not only from Turkey, but from southeastern Europe and the Eastern Mediterranean basin as a whole. These rare records provide important information about the dispersal routes of anguines from Europe to Asia and significantly enhance our understanding of their biogeography

First fossil find of the Blanus strauchi complex (Amphisbaenia, Blanidae) from the Miocene of Anatolia

WOS: 000432213400008SYNTHESYS [SYNTHESYS ES-TAF-5910]; Ege University Research ProjectsEge University [TTM/001/2010, TTM/002/2011, TTM/001/2013, TTM/002/2014, 2015/Fen/17]; [TUBITAK-RFBR 111Y192]We would like to thank P. Lymberakis (NHMC), M. Calvo Revuelta (MNCN), and G. Gassner and C. Horweg (NHMW) for providing access to specimens under their care and photographs of extant specimens of Blanus spp. M. Delfino (University of Torino) provided insightful comments that enhanced the quality of the manuscript. A. Villa (University of Torino) helped with the literature. G.L.G. acknowledges travel support from SYNTHESYS (grant SYNTHESYS ES-TAF-5910) and the University of Torino. K.H., S.M., and T.K. were supported by TUBITAK-RFBR 111Y192 and Ege University Research Projects TTM/001/2010, TTM/002/2011, TTM/001/2013, TTM/002/2014, and 2015/Fen/17 during their field trips. We also thank Editor J. Head and the reviewers A. Bolet and J. Muller for their comments and help during the review process

Early Miocene gastropod and ectothermic vertebrate remains from the Lesvos Petrified Forest (Greece)

The Lesvos Petrified Forest (western Lesvos, Greece) has long been famous for its plant fossils. Recently, one proboscidean (from the Gavathas locality) and seven micromammalian species (from the Lapsarna locality) were described; these were the first animals to be found in the Early Miocene subtropical forest. For the first time, a fauna of gastropods and ectothermic vertebrates from the Lapsarna locality is now available. This fauna derives from lacustrine sediments under the pyroclastic material that contains the petrified plants. Based on fragmented mollusc remains, isolated fish pharyngeal teeth and utricular otoliths (lapilli), fragmented amphibian vertebrae and a tooth-bearing element, and reptile fragmented dentaries, teeth, osteoderms and vertebrae, the presence of eight freshwater and three terrestrial gastropod species, three freshwater cyprinid species, and two amphibian and five reptile taxa has been confirmed. Stratigraphical and radiometric data suggest an age older than 18.4 ± 0.5 Ma (latest Early Miocene), in good agreement with the faunal composition. This paper is the first report of the concurrent presence of three cyprinid fish species in a Greek Early Miocene locality, as well as the first documentation of an Early Miocene proteid amphibian in southeastern Europe. The present findings represent one of the best- documented Early Miocene gastropod and fish faunas in the Aegean/southern Balkans, thus adding to our knowledge of Early Miocene amphibians and reptiles from that region and providing valuable information on the local subtropical ecosystem

Assessing the relevance of different sources of variability on the survival of foodborne pathogens: stress adaptation against genetic heterogeneities

[SPA] La evaluación de riesgos microbianos es crucial para proteger la salud pública, así como para que la cadena de suministro de alimentos sea eficiente. La evaluación debe considerar varias fuentes variabilidad en la respuesta microbiana, tales como la adaptación al estrés y las heterogeneidades genéticas, ya que éstas pueden afectar la supervivencia, el crecimiento y la virulencia de los patógenos alimentarios influyendo a su capacidad para causar enfermedades en humanos o alteraciones en los alimentarios. Actualmente existen grandes lagunas de conocimiento en cuanto a la variabilidad de la respuesta microbiana, por lo que su elucidación es esencial para una estimación precisa del riesgo, así como para el desarrollo de medidas de control eficaces. En base a esto, esta tesis de doctorado tiene como objetivo evaluar y comparar la importancia de la adaptación al estrés y las heterogeneidades genéticas en los microorganismos para la supervivencia de las bacterias a los tratamientos térmicos. En el Capítulo I se estudia la inactivación térmica de dos cepas de Salmonella (Salmonela Enteritidis CECT4300 y Senftenberg CECT4565) tanto en condiciones isotérmicas como dinámicas. Para los tratamientos isotérmicos, se encontró que S. Senftenberg era mucho más resistente que S. Enteritidis (por un factor de aproximadamente 10). También observamos diferencias cualitativas: las curvas de supervivencia isotermas de la cepa de S. Senftenberg fueron de tipo Weibull, mientras que el modelo Bigelow (lineal) fue capaz de describir la respuesta de S. Enteritidis. Así mismo, los modelos basados en experimentos isotérmicos fueron capaces de describir la inactivación dinámica de S. Senftenberg, mientras que S. Enteritidis necesitó de un modelo dinámico que consideraba la aclimatación del estrés. El estudio destaca que, además de la variabilidad cuantitativa, la inactividad microbiana también tiene una componente cualitativa. Esto enfatiza la importancia de considerar diferentes hipótesis de modelo para las condiciones isotérmicas y dinámicas. El Capítulo II va más allá en la inactivación térmica de Salmonella spp. centrándose en la importancia de la variabilidad fenotípica en la evaluación del riesgo microbiano. Esta fuente de variabilidad incluye las diferencias en el estado fisiológico de diferentes células de las mismas especies bacterianas debido a una exposición previa a diferentes entornos. Se estudió tanto el impacto de las condiciones de pre-cultivo subóptimas en la resistencia térmica de las mismas dos cepas de Salmonella como el efecto de un choque ácido. Los resultados muestran que la variabilidad fenotípica también es dependiente de la cepa. Para la cepa de Salmonella altamente resistente (S. Senftenberg), se observó una reducción de la resistencia térmica con respecto a las condiciones óptimas de incubación. Por otro lado, las condiciones de incubación subóptimas tuvieron el efecto opuesto en la cepa de referencia (S. Enteritidis), aumentando su resistencia térmica a través de la inducción de mecanismos de resistencia cruzada. En base a estos resultados, el estudio sugiere que la variabilidad fenotípica debería ser un aspecto central en la microbiología predictiva y la evaluación de riesgos, e ilustra un ejemplo hipotético de incorporación de esta fuente de variabilidad en el análisis de riesgos vinculando las condiciones pre-cultivo al origen de la contaminación bacteriana. El Capítulo III utiliza un organismo modelo (Bacillus subtilis) para profundizar en el estudio de las diferencias entre la inactivación bacteriana bajo condiciones isotermas y dinámicas. Con el objetivo de relacionar la respuesta microbiana observada a nivel poblacional con información a nivel molecular, se realizaron experimentos utilizando tanto una cepa silvestre como un mutante “sigB null”. Se observaron curvas de supervivencia con una curvatura hacia arriba, que a menudo se atribuye a la heterogeneidad en la resistencia térmica (hipótesis vitalística). Sin embargo, las curvas de inactivación tras la aplicación de un pretratamiento fueron log-lineales, indicando la adaptación dinámica al estrés durante el tratamiento isotérmico como una posible explicación de la curvatura observada. Esta interpretación de los resultados permite definir, en base a resultados isotermos, límites para la adaptación microbiana que se pueda desarrollar durante un tratamiento dinámico. Por lo tanto, este estudio proporciona una interpretación alternativa de las curvas de supervivencia bajo condiciones isotermas que podría llegar a mejorar nuestra capacidad de predecir la respuesta microbiana durante los tratamientos de pasteurización. [ENG] Microbial risk assessment is crucial for protecting public health and the food supply chain. Sources of variability in microorganisms, such as stress adaptation and genetic heterogeneities, can affect the survival, growth and virulence of microorganisms, and their ability to cause disease or food spoilage. There are currently large knowledge gaps regarding variability of the microbial response, and understanding it is essential for accurately estimating potential risks and to develop effective control measures. In light of this, this PhD thesis aims to compare and evaluate the importance of stress adaptation and genetic heterogeneities in microorganisms for the survival of bacteria to thermal treatments. Chapter I discusses the thermal inactivation of two Salmonella strains (Salmonella Enteritidis CECT4300 and Salmonella Senftenberg CECT4565) under both isothermal and dynamic conditions. For isothermal treatments, S. Senftenberg was found to be much more resistant than S. Enteritidis (by approximately a factor of 10). We also observed qualitative differences, with the inactivation models used to describe the response of S. Senftenberg were weibullian, while the Bigelow model was successful in describing the isothermal response of S. Enteritidis. Models based on isothermal experiments were able to describe dynamic inactivation of S. Senftenberg, while S. Enteritidis required a dynamic model that considered stress acclimation. The study highlights that, besides quantitative, variability in microbial inactivation is also qualitative. This underlies importance of considering different model hypotheses for both isothermal and dynamic conditions. Chapter II goes further in the thermal inactivation of Salmonella spp. focusing on the importance of phenotypic variability in microbial risk assessment, which refers to the physiological differences of cells of the same bacterial species due to prior exposure to different environments. The impact of sub-optimal pre-culture conditions or the application of an acid shock on the thermal resistance of the same two Salmonella strains was studied, founding that phenotypic variability is also strain-dependent. For the highly resistant strain (S. Senftenberg), the conditions tested resulted in a reduction of thermal resistance with respect to optimal incubation conditions. On the other hand, sub-optimal incubation conditions had the opposite effect on the reference strain (S. Enteritidis), increasing its thermal resistance through the induction of cross-resistance mechanisms. The study suggests that phenotypic variability should be a main focus in predictive microbiology and risk assessment, and illustrates a hypothetical example of how this could be achieved in practice by linking pre-incubation conditions to the origin of bacterial contamination. Chapter III uses a common model organism (Bacillus subtilis) to further study the differences between isothermal and dynamic bacterial inactivation. To link differences in the response to molecular mechanisms, experiments were made using both a wild type strain and a marker-free sigB null mutant. Survivor curves with an upward curvature were observed, which is often attributed to heterogeneity in thermal resistance (vitalistic hypothesis). However, a pretreatment resulted in log-linear survivor curves, indicating dynamic stress adaptation during the isothermal treatment as a possible explanation for the upward curvature. Based on this hypothesis, bounds were defined based on isothermal experiments to account for acclimation under dynamic conditions. The study provides an alternative interpretation for survivor curves, which can improve predictions of microbial response during pasteurization treatments.Escuela Internacional de Doctorado de la Universidad Politécnica de CartagenaUniversidad Politécnica de CartagenaPrograma de Doctorado en Técnicas Avanzadas en Investigación y Desarrollo Agrario y Alimentari