Characterization of rhodolith beds-related backscatter facies from the western Pontine Archipelago (Mediterranean Sea).

Rhodoliths (nodular calcareous red algae) are considered one of the most important bioengineers in the Mediterranean Sea, making rhodolith beds ecologically relevant ecosystems. On the insular shelf surrounding the western Pontine Archipelago (depth from 43 to 112 m), rhodolith beds were identified through the analysis of an extensive dataset of grab samples and videos to ground-truth the backscatter acoustic facies. Six acoustic facies (low backscatter, dishomogeneous low-backscatter, dishomogeneous high-backscatter, high-backscatter, rocks and high backscatter, and rocks and medium backscatter) were recognized. We studied how rhodoliths characteristics (density, morphotype, size and structure) differently influence the backscatter signature. At the western Pontine Archipelago, rhodolith beds are mainly represented by facies dishomogeneous high backscatter, high backscatter, high backscatter with rocks, and medium backscatter with rocks. The obtained results increase both the knowledge on the heterogeneous structure of such ecologically relevant benthic habitat and highlight the use of distinctive acoustic facies for their identification. Finally, the used approach could be considered a useful method for indirect detection and mapping of rhodolith beds.

Coralline algae on hard and soft substrata of a temperate mixed siliciclastic-carbonatic platform: Sensitive assemblages in the Zannone area (western Pontine Archipelago; Tyrrhenian Sea).

In the Mediterranean Sea, coralline algae assemblages (i.e. rhodolith beds and coralligenous assemblages) are considered biodiversity hotspots comparable to tropical reefs. However, information regarding their environmental distribution is still poor. In this view, relevant international actions have been adopted by the European Union to fill this gap. This work represents one of a few cases of predictive (fine-scale) habitats distribution map obtained through an integrated semi-automatic approach based on bathymetry, backscatter, seismic profiles, video, and sampling data. The used method has permitted the identification of nine morphological zones, four backscatter facies, and four benthic habitats distributed on the Zannone seafloor (western Pontine Archipelago; Tyrrhenian Sea). In particular, the finding of widespread sensitive habitats (i.e. coralligenous assemblages and rhodolith beds) reveals as the marine area off the western Pontine Archipelago (Tyrrhenian Sea) is highly suitable for their development (distance from the mainland, lack of river mouths), confirming the relevant ecological value of the Zannone area. Therefore, such information constitutes an update to the Mediterranean habitats distribution inventory, highlighting the need for the application of protection actions possibly targeted in the establishment of a Marine Protected Area.

Effects of anthrax lethal toxin on human primary keratinocytes.

AIMS: To investigate the effects of anthrax lethal toxin (LeTx) on human primary keratinocytes. METHODS AND RESULTS: We show here that human primary keratinocytes are resistant to LeTx-triggered cytotoxicity. All but one of the MEKs (mitogen-activated protein kinase kinases) are cleaved within 3 h, and the cleavage of MEKs in keratinocytes leads to their subsequent proteasome-mediated degradation at different rates. Moreover, LeTx reduced the concentration of several cytokines except RANTES in culture. CONCLUSIONS: Our results indicate that primary keratinocytes are resistant to LeTx cytotoxicity, and MEK cleavage does not correlate with LeTx cytotoxicity. Although LeTx is considered as an anti-inflammatory agent, it upregulates RANTES. SIGNIFICANCE AND IMPACT OF THE STUDY: According to a current view, the action of LeTx results in downregulation of the inflammatory response, as evidenced by diminished expression of several inflammatory biomarkers. Paradoxically, LeTx has been reported to attract neutrophils to cutaneous infection sites. This paper, which shows that RANTES, a chemoattractant for immune cells, is upregulated after exposure of keratinocytes to LeTx, although a number of other markers of the inflammatory response are downregulated. Our results might explain why the exposure of keratinocytes to LeTx results in the recruitment of neutrophils to cutaneous infection sites, while the expression of several inflammatory biomarkers is diminished.

Normal human keratinocytes pretreated with damaged mRNA are resistant to UVB damage and exhibit increased DNA repair.

Treatment of normal human keratinocytes with UVC-irradiated rabbit globin mRNA 24 h before and after UVB exposure increased the survival of the human keratinocytes. We also observed that UVC-damaged mRNA reduced the formation of sunburn cells in skin models. We next tested the effects of UVC-damaged mRNA on cellular repair of DNA. DNA repair was evaluated using 2 assay methods. The first method used a damaged plasmid that is transfected back into the cell where it is repaired by the host cell repair mechanism. In these experiments, we observed that externally added UVC-damaged rabbit globin mRNA enhanced the repair of a plasmid transfected into the host keratinocyte cells. The second method used to determine the effects on DNA repair was direct immunostaining for thymidine-thymidine dimers (TT dimers) in histological sections of the skin models. Skin models were irradiated with UVB and then fixed immediately or after 24 h and stained for TT dimers. UVB irradiation immediately caused an increase in the number of stained keratinocytes in the skin. The number of stained cells decreased in skin fixed 24 h after UVB. This is due to repair of the TT dimers and their removal. Sections of skin models pretreated with UV-damaged mRNA exhibit greater removal of these TT dimers after 24 h. The above evidence suggests that damaged mRNA can trigger a host cell DNA repair pathway.

Protection against cigarette smoke-induced damage to intact transformed rabbit corneal cells by N-acetyl-L-cysteine.

In order to assess cigarette smoke-induced oxidative damage to intact cells, an assay was developed to measure cell detachment and protection. Due to the complex nature of cigarette smoke, which contains molecules that can interfere with conventional spectrophotometric and fluorometric biochemical assays, transformed rabbit corneal cells were radiolabeled with tritiated thymidine and then subjected to direct stream smoke. As a result, cell damage in response to the smoke from only two cigarettes could be measured in a time-dependent manner. When cells were prelabeled with N-acetyl-L-cysteine (NAC), a substrate for glutathione synthesis, a significant reduction in damage was measured. Additionally, when buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, was incubated with cells, a reduction in the effectiveness of NAC was observed, although NAC still retained some activity. Furthermore, vitamin E conferred no protection to cells in this system nor was NAC active in a separate assay that appears to favor peroxyl radical generation. From these results we conclude that cigarette smoke damage can easily be determined at the cellular level with this technique and that NAC acted to prevent this damage in two ways: first, as glutathione precursor and, secondly, as an antioxidant capable of scavenging non-peroxyl radicals.