Climate reconstructions and monitoring in the Mediterranean Sea: A review on some recently discovered high-resolution marine archives

Palaeoclimate records are important tools for understanding climate modifications and contextualizing recent anthropogenic perturbations in climate change relative to natural variability in the Earthclimate system. Moreover, time-series proxy records of the main physical and chemical parameters in marine and continental environments are increasingly used for testing climate models in order to ascertain the reliability of projections for future scenarios in our greenhouse modified Earth. In order to account for the limited number of continuous instrumental measurements of climatic variables in the past, such as sea surface temperature (SST), salinity (SSS), sea-level fluctuations and water chemistry, a complementary approach is the examination of geochemical tracers (i.e. trace elements and stable isotopes) in well-dated natural marine archives. Recently, the Mediterranean Sea has been the focus of a number of studies where new high resolution climate archives have been investigated utilizing proxies for sea surface temperature, salinity,marine chemistry, and ocean circulation, different to those available for tropical regions. In particular, vermetids (Dendropoma petraeum), non-tropical zooxanthellate corals (Cladocora caespitosa) and cold-water corals (Desmophyllum dianthus, Lophelia pertusa and Madrepora oculata) have been studied by conventional and advanced analytical techniques (e.g., laser ablation ICP-MS, MC-ICP-MS, synchrotron X-ray fluorescence) and have been successfully used as high-resolution palaeoenvironmental proxies. Vermetid reefs have the potential to yield valuable information on past sea-level changes and SST, through the combination of stable isotopes and radiocarbon dating. The trace element concentration, in combination with U-series and radiocarbon dating, of the skeletal aragonite of the Mediterranean zooxanthellate coral Cladocora caespitosa, and of the coldwater corals Desmophyllum dianthus and Lophelia pertusa, has been successfully demonstrated to be a valid high-resolution SST archive, and a seawater chemistry and ocean circulation proxy, respectively. Here we present a review of our research over the last few years, aiming for the establishment of new natural marine archives collected from various sites of the Mediterranean Sea, reporting on our methodological approaches and main results.      

Tracheal occlusion increases the rate of epithelial branching of embryonic mouse lung via the FGF10-FGFR2b-Sprouty2 pathway

Tracheal occlusion during lung development accelerates growth in response to increased intraluminal pressure. In order to investigate the role of internal pressure on murine early lung development, we cauterized the tip of the trachea, to occlude it, and thus to increase internal pressure. This method allowed us to evaluate the effect of tracheal occlusion on the first few branch generations and on gene expression. We observed that the elevation of internal pressure induced more than a doubling in branching, associated with increased proliferation, while branch elongation speed increased 3-fold. Analysis by RT-PCR showed that Fgf10, Vegf, Sprouty2 and Shh mRNA expressions were affected by the change of intraluminal pressure after 48h of culture, suggesting mechanotransduction via internal pressure of these key developmental genes. Tracheal occlusion did not increase the number of branches of Fgfr2b-/- mice lungs nor of wild type lungs cultured with Fgfr2b antisense RNA. Tracheal occlusion of Fgf10(LacZ/-) hypomorphic lungs led to the formation of fewer branches than in wild type. We conclude that internal pressure regulates the FGF10-FGFR2b-Sprouty2 pathway and thus the speed of the branching process. Therefore pressure levels, fixed both by epithelial secretion and boundary conditions, can control or modulate the branching process via FGF10-FGFR2b-Sprouty2.     

Sensory or sympathetic white adipose tissue denervation differentially affects depot growth and cellularity

Functional and histological evidence for the sympathetic nervous system (SNS) innervation of white adipose tissue (WAT) exists for several species; however, its sensory innervation has only been shown in laboratory rats, and its function is unclear. We tested the effects of sensory and SNS innervation of Siberian hamster epididymal and inguinal WAT (EWAT and IWAT) by assessing calcitonin gene-related peptide (CGRP)- and tyrosine hydroxylase-immunoreactivity (ir), respectively. Next, we tested the role of the sensory innervation of WAT on growth and cellularity because WAT surgical denervation increases pad mass via selective increases in fat cell number, an effect ascribed to SNS denervation but that could be due to the accompanying surgical disruption of WAT sensory innervation. Sensory denervation was accomplished via multiple local microinjections of capsaicin into WAT, and its effects were compared with those of surgical denervation. Surgically denervated IWAT and EWAT showed significantly decreased tyrosine hydroxylase-ir and CGRP-ir, whereas capsaicin-treated WAT had only significantly decreased CGRP-ir. Surgically denervated pad masses were significantly increased; this was accompanied by increased total fat cell number in IWAT, with no change in fat cell size. EWAT only showed a significant increase in the number of small- to medium-sized adipocytes (75-125 mum diameter). By contrast, sensory-denervated pad masses were unchanged, but IWAT showed significantly increased average fat cell size. Collectively, these data provide immunohistochemical evidence for sensory and SNS innervation of WAT in Siberian hamsters and differential control of WAT cellularity by these innervations, as well as the ability of locally applied capsaicin to selectively reduce WAT sensory innervation.     

Fgf10 expression identifies parabronchial smooth muscle cell progenitors and is required for their entry into the smooth muscle cell lineage

Lineage formation in the lung mesenchyme is poorly understood. Using a transgenic mouse line expressing LacZ under the control of Fgf10 regulatory sequences, we show that the pool of Fgf10-positive cells in the distal lung mesenchyme contains progenitors of the parabronchial smooth muscle cells. Fgf10 gene expression is slightly repressed in this transgenic line. This allowed us to create a hypomorphic Fgf10 phenotype by expressing the LacZ transgene in a heterozygous Fgf10 background. Hypomorphic Fgf10 mutant lungs display a decrease in beta-galactosidase-positive cells around the bronchial epithelium associated with an accumulation of beta-galactosidase-expressing cells in the distal mesenchyme. This correlates with a marked reduction of alpha smooth muscle actin expression, thereby demonstrating that FGF10 is mostly required for the entry of mesenchymal cells into the parabronchial smooth muscle cell lineage. The failure of exogenous FGF10 to phosphorylate its known downstream targets ERK and AKT in lung mesenchymal cultures strongly suggests that FGF10 acts indirectly on the progenitor population via an epithelial intermediate. We provide support for a role of epithelial BMP4 in mediating the formation of parabronchial smooth muscle cells.     

Effects of environmental benzene: micronucleus frequencies and haematological values in traffic police working in an urban area

Among the toxic chemicals present in the ambient air of urban centres, benzene raises particular concern due to its haematoxicity and leukaemogenic hazards, probably related to clastogenic factors. However, little is known about the health risks associated with environmental--rather than industrial--exposure to benzene. We analysed micronucleus (MN) frequencies in peripheral lymphocytes by use of the cytokinesis-block technique, and haematological parameters among 49 traffic police and 36 indoor workers (controls) in the city of Bologna. The analysis of urban air provided by a municipal air-quality monitoring station indicated that the levels of environmental benzene were often above the recommended threshold level (10 microg/m3) whereas other pollutants--nitrogen oxides, polycyclic aromatic hydrocarbon compounds, total suspended particulate matter, carbon monoxide, sulfur dioxide--did not exceed the maximum atmospheric concentration established for air-quality standards. Mean levels of individual airborne benzene exposure--as measured by personal devices worn during 4-h morning work-shifts--were six-fold higher in the traffic police than in controls (P=0.001). While no significant difference in haematological parameters was found between the two groups, MN frequency was significantly higher among the traffic police than in indoor workers (P=0.001). Among the study population, MN frequency was found to increase with age, but no influence was observed for gender or smoking. Although it cannot be excluded that the increase of MN frequency observed in traffic police could also depend, apart from benzene, on the complex mixture of pollutants encountered in urban air, our data indicate that elevated personal benzene exposure could represent a genetic risk. The analysis of biomarkers of genetic damage in subjects particularly exposed to environmental benzene deserves careful study.     

Micronuclei in humans induced by exposure to low level of ionizing radiation: influence of polymorphisms in DNA repair genes

Understanding the risks deriving from protracted exposure to low doses of ionizing radiation has remarkable societal importance in view of the large number of work settings in which sources of IR are encountered. To address this question, we studied the frequency of micronuclei (MN), which is an indicator of DNA damage, in a population exposed to low levels of ionizing radiation and in matched controls. In both exposed population and controls, the possible influence of single nucleotide polymorphisms in XRCC1, XRCC3 and XPD genes on the frequency of micronuclei was also evaluated. We also considered the effects of confounding factors, like smoking status, age and gender. The results indicated that MN frequency was significantly higher in the exposed workers than in the controls [8.62+/-2.80 versus 6.86+/-2.65; P=0.019]. Radiological workers with variant alleles for XRCC1 or XRCC3 polymorphisms or wild-type alleles for XPD exon 23 or 10 polymorphisms showed a significantly higher MN frequency than controls with the same genotypes. Smoking status did not affect micronuclei frequency either in exposed workers or controls, while age was associated with increased MN frequency in the exposed only. In the combined population, gender but not age exerted an influence on the yield of MN, being higher in females than in males. Even though there is a limitation in this study due to the small number of subjects, these results suggest that even exposures to low level of ionizing radiation could have genotoxic effects and that XRCC3, XRCC1 and XPD polymorphisms might contribute to the increased genetic damage in susceptible individuals occupationally exposed to chronic low levels of ionizing radiation. For a clear conclusion on the induction of DNA damage caused by protracted exposure to low doses of ionizing radiation and the possible influence of genetic polymorphism in DNA repair genes larger studies are needed.     

Adipocyte death defines macrophage localization and function in adipose tissue of obese mice and humans

Macrophage infiltration of white adipose tissue (WAT) is implicated in the metabolic complications of obesity. The precipitating event(s) and function(s) of macrophage infiltration into WAT are unknown. We demonstrate that >90% of all macrophages in WAT of obese mice and humans are localized to dead adipocytes, where they fuse to form syncytia that sequester and scavenge the residual "free" adipocyte lipid droplet and ultimately form multinucleate giant cells, a hallmark of chronic inflammation. Adipocyte death increases in obese (db/db) mice (30-fold) and humans and exhibits ultrastructural features of necrosis (but not apoptosis). These observations identify necrotic-like adipocyte death as a pathologic hallmark of obesity and suggest that scavenging of adipocyte debris is an important function of WAT macrophages in obese individuals. The frequency of adipocyte death is positively correlated with increased adipocyte size in obese mice and humans and in hormone-sensitive lipase-deficient (HSL-/-) mice, a model of adipocyte hypertrophy without increased adipose mass. WAT of HSL-/- mice exhibited a 15-fold increase in necrotic-like adipocyte death and formation of macrophage syncytia, coincident with increased tumor necrosis factor-alpha gene expression. These results provide a novel framework for understanding macrophage recruitment, function, and persistence in WAT of obese individuals.     

Xantusiid "night" lizards: a puzzling phylogenetic problem revisited using likelihood-based Bayesian methods on mtDNA sequences

Contentious issues in Night Lizard (Xantusiidae) evolution are revisited using Maximum Likelihood-based Bayesian methods and compared with results from Neighbor-Joining and Maximum Parsimony analyses. Fragments of three mitochondrial genes, the 12S and 16S ribosomal genes, and the cytochrome b gene, are sampled across an ingroup composed of seven xantusiid species and a 12-species outgroup chosen to bracket ancestral states for six additional clades of scleroglossan lizards. Our phylogenetic analyses afford robust support for the following conclusions: Xantusiidae is part of Scincomorpha, rather than being allied with Gekkota; Lepidophyma is sister to Xantusia, rather than to Cricosaura; Xantusia riversiana is imbedded within, rather than being sister to, other Xantusia species; and rock-morph Xantusia are not closely related to one another. Convergence related to retarded rates of growth and development, or to physical constraints imposed by living in rock crevices, may be responsible for much of the character discordance underlying conflicts in xantusiid phylogeny. Fossil-calibrated Maximum Likelihood-based divergence time estimates suggest that although the xantusiid stem may have originated in the Mesozoic, the crown clade is exclusively Tertiary in age. Thus, the clade including extant Cricosaura does not appear to have been extant during the K-T boundary bolide impact, as has been suggested. Moreover, our divergence-time estimates indicate that the xantusiid island endemics, Cricosaura typica on Cuba and Xantusia riversiana on the California Channel Islands, arrived via dispersal rather than vicariance, as previously proposed.     

Helicobacter pylori infection in children and adults: a single pathogen but a different pathology

Background. The aims of this retrospective study were to ascertain in large series of children and adults: the relationship of the infecting strain to gastric mucosal lesions; and the relationship of the infecting strain to its duodenal localization. Materials and Methods. We studied 307 and 604 consecutive children and adults. In gastric mucosal samples H. pylori was cultured, genotyped and histologically assessed, while inflammation, activity and intestinal metaplasia were graded. In a subset of 171 patients H. pylori ureaseA (ureA) and cagA genes were amplified (PCR) using mucosal biopsies from the duodenum. Results. H. pylori infection was diagnosed in 40 children and 308 adults. cagA was identified in 50% and 65.5% of infected children and adults. Antral activity was associated with the density of infecting bacteria (p < .001) and with cagA (p < .01). Intestinal metaplasia was correlated with cagA (p < .001). The ureA gene was found in 56 duodenal samples from 82 H. pylori positive patients. Duodenal H. pylori ureA was significantly more frequent in patients with duodenal diseases than in those without (p < .01), cagA positive strains being mainly involved in the infection of this anatomical area (p < .01). Conclusions. A severe H. pylori‐associated gastritis is more prevalent when the density of infecting bacteria is high and when cagA positive strains cause the infection. The most virulent cagA positive H. pylori colonizes not only the gastric, but also the duodenal mucosa, which can be directly damaged by the bacteria itself or by its products.